Melo Melo Pearls

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Origin of Name :-'

Melo Melo pearls originate from a gastropod mollusk known as the melo-melo sea-snail or bailer volute

Melo Melo pearls are extremely rare non-nacreous pearls produced by the gastropod mollusk commonly known as the melo-melo sea snail, zebra sea-snail or bailer volute, belonging to the family Volutidae, and given the scientific name Melo melo. Thus melo melo pearls derive their name from the scientific name of the sea-snail that produces them. The sea-snail earned its name "bailer volute" because the large shell of the snail was often used to bail water out of boats. It should be noted that the Melo melo snail belongs to the Phylum Mollusca, under which there are three main classes, the Bivalvia (oysters, mussels, clams, scallops etc.), the Gastropoda ( sea-snails, land snails, slugs, periwinkles, whelks and abalone etc.), and the Cephalopoda (octopus, squids, cuttle fish and nautilus ).

Thus sea-snails such as Melo melo (bailer volute), Strombus gigas (queen conch) and Pleuroploca gigantea (horse conch), that are known to produce non-nacreous pearls, belong to the gastropod mollusks. In this context the following statement made in some popular pearl websites, is  both confusing and totally misleading :-"The melo melo "pearl" does not come from an oyster or mollusk, but comes instead from the melo melo marine snail" Undoubtedly, the melo melo pearl does not originate in an oyster, which is a bivalve mollusk, but in the same breath the statement declares, that the pearl does not arise in a mollusk either. The statement continues that the pearl originates in the melo melo marine snail. The statement is contradictory, and whoever who made it, apparently doesn't seem to know, that melo melo marine snails are also mollusks falling under the class gastropoda.

A Shell of Melo melo sea-snail with a group of melo-melo pearls

A Shell of Melo melo sea-snail with a group of melo-melo pearls

Photo Above Creative Commons

Melo Melo pearls are non-nacreous pearls

What distinguishes a "true pearl" from non-nacreous pearls ?

Being produced by a gastropod mollusk like conch pearls, melo melo pearls do not qualify to be classified under "true pearls," a term reserved only for nacreous pearls produced by bivalve mollusks, such as saltwater oysters and freshwater mussels. Even pearls produced by certain clams such as the quahog clam, which are also bivalve mollusks are not considered to be "true pearls" as they are non-nacreous. Thus, what actually distinguishes a true pearl from a non-nacreous pearl, previously known as calcareous concretions, is the presence or absence of "nacre," an organic/inorganic complex material, that imparts the unique luster and iridescence, characteristic of these pearls.

Intense-orange melo-melo pearl

Intense-orange melo-melo pearl

The composition of nacre and what causes the characteristic luster and iridescence

The organic component of nacre is the scleroprotein conchiolin, while the inorganic component is crystalline calcium carbonate, mainly aragonite together with some calcite. Aragonite is found mainly as tiny hexagonal platelets with a  width of 10-20 µm and thickness of 0.5 µm. These platelets are arranged in parallel lamina, separated by conchiolin. The thickness of the aragonite platelets, is comparable to the wavelength of visible light, causing the scattering of different colors in white light, producing the characteristic iridescent effect.

The composition of non-nacreous pearls, and reasons for absence of iridescence and presence of chatoyancy

In non-nacreous pearls, the pearl forming substance is chemically related to nacre, but the crystalline form of calcium carbonate that forms the inorganic component is mainly calcite and not aragonite. Moreover, the calcite microcrystals do not form tiny hexagonal platelets but long needles that do not scatter light. Hence, the absence of iridescence in non-nacreous pearls. The microcrystalline calcite needles are associated together to form  bundles of fibers, whose arrangement and alignment, causes a type of "chatoyancy" when light falls on the fibers, known as a "flame structure." In melo melo pearls, particularly the most sought-after intense orange-hued ones, the effect of the shimmering flame structure, combined with the porcellaneous luster is spectacular, even surpassing the beauty of some nacreous pearls, that has triggered a debate whether the continued classification of these rare beauties of nature, as non-nacreous pearls is justified.      

Yellowish-orange melo-melo pearl

Yellowish-orange melo-melo pearl

The natural habitat of the Melo melo sea snail

The geographic range of the Melo melo sea-snail - the Indo-Pacific region

The natural habitat of the Melo melo sea-snail are the seas of the Southeast Asian region, the South China Sea, the Gulf of Thailand, the Andaman Sea, and the Bay of Bengal closer to Burma. The waters off Vietnam in the South China Sea, is a well known habitat of the sea-snail, a primary source of the rare melo-melo pearls produced by these sea snails. Other habitats include the waters off Thailand in the Gulf of Thailand; Burma in the Bay of Bengal; the Andaman Islands in the Andaman Sea; Cambodia, Malaysia, Singapore, Indonesian archipelago and Philippines in the South China Sea. They are also found off the coast of Northern Australia, in the South China Sea. This region where the sea-snail occurs is known as the Indo-Pacific region, and the South China Sea, is the sea that connects the Indian  and  Pacific Oceans.

Melo melo sea snail at Beting Bronok, Singapore

Melo melo sea snail at Beting Bronok, Singapore

©Wild singapore .COM

The main areas in Vietnam where the sea-snails are found abundantly

In Vietnam, the Melo-melo snail is found in the waters of the picturesque Halong Bay - the "Bay of Dragons," along the northern coast of Vietnam. Within the bay itself an area that is rich in melo sea-snails are the sand banks around the Bach Long Vi islands, a small island located halfway between Haipong and Hainan Island. However, most of the sea-snails that are harvested in Vietnam by trawlers originating from the fishing harbors of Thanh Hoa and Quang Ngai  come from the waters surrounding the distant islands of Spartly and Paracel in the South China Sea, two groups of islands whose ownership is disputed between Vietnam and China. The sea-snails are found in sandy and rocky areas at depths of 20-30 meters. The peak fishing period for melo melo snails is around April. The snails that are harvested are transported to the northern Cat Ba Islands, the main trading center for sea-snails harvested from all over Vietnam, from where dealers who purchase the snails from the fisherman export them to China. However, after about 20 years of intensive trawler fishing of the sea-snails, their harvest has been drastically reduced, and concurrently melo-melo pearls which were relatively common in the past are becoming scarcer and scarcer. Vietnam being the primary source of Melo melo pearls, the pearls are also sometimes referred to as Vietnamese orange pearls.

Young Melo melo sea snail on the shores of Beting Bronok, Singapore

Young Melo melo sea snail on the shores of Beting Bronok, Singapore

©Wild singapore .COM

The areas in Burma where they are found abundantly

In Burma, Melo melo sea-snails are found along the Arkan coast, in the southern region of Dawei, the Mergui Archipelago, and Kawthaung in the Andaman Sea near Thailand. The shells of the snail are known as "ohn kayu" or "coconut shell" because of their resemblance to coconuts, and the pearls produced by them are known as "ohn pale" meaning "coconut pearls." The Melo melo sea-snails are fished at a depth of 30-50 meters from the muddy sea bottom.

The occurrence of Melo melo snails in Thailand

In Thailand, Melo melo snails are brought up occasionally from the bottom of the sea, while fishing for crabs in the Gulf of Thailand. One reason why the sea-snail is difficult to find is because it usually inhabits the muddy bottoms of the sea, at depths of over 20 meters, where it leads the life of a predator feeding on other small gastropods and sea creatures. However, according to a Thai scientist Mr. Suraphol Chunhabundit, marine biologist at the Chulalongkorn University in Bangkok, the Melo melo sea-snail is nocturnal and during the daytime digs itself into the sandy bottom leaving only a siphon above the sand. This is precisely the reason why it is very hard to find and is rarely caught. According to him the snail feeds on plankton and other small animals at the bottom of the sea.

The occurrence of Melo melo snails in Singapore and Malaysia

Two species of volutes have been recorded in the waters off Singapore and Malaysia - the bailer volute, Melo melo and the noble volute, Cymbiola nobilis. While the noble volutes are sometimes seen in the undisturbed northern shores, the bailer volutes are seldom seen at all, mainly because they inhabit deeper waters. The bailer volute in Singapore is commonly encountered on the remote offshore reef of Beting Bronok. The bailer volute is listed as an endangered species in Singapore, mainly due to habitat loss.

The Melo melo sea-snail


Phylum       :  Mollusca

Class         :   Gastropoda

Subclass     :  Orthogastropoda

Order         :  Sorbeoconcha

Sub-order   :  Hypsogastropoda

Superfamily :  Volutoidae

Family        :  Volutidae

Genus        :  Melo

Species      :  melo

Common names : Indian Volute

                     :  Bailer Volute

                     :  Zebra Sea-Snail

Habitat - The Melo melo sea-snails are found in the sandy or muddy bottoms in the infra-littoral and circa-littoral sub-zones of the sub-littoral zone

The sub-littoral zone

The habitat of the Melo melo sea-snail in the Indo-Pacific region usually extends from the seashore to a depth of about 70 to 80 meters in the sub-littoral zone. They are predominantly found in the sandy or muddy bottoms in  the infra-littoral and circa-littoral sub-zones, of the sub-littoral zone.

The sub-littoral zone, begins immediately after the inter-tidal zone and extends to the edge of the continental shelf, to a depth of about 200 meters. In this region sunlight reaches the ocean floor, and makes possible the survival of photosynthetic organisms such as phytoplankton and sea weeds and grasses. The area is also rich in oxygen, has low water pressures and relatively stable temperatures and salinity levels. Thus the sub-littoral zone also known as the Neritic zone is the location of the majority of sea life, that includes the phytoplankton, the base of the food pyramid, that supports fish life, and other forms of sea life such as crustaceans, mollusks etc. The submerged coral reefs are also found in this region.

The infra-littoral zone

The sub-littoral zone is divided into infra-littoral and circa-littoral zones, by marine biologists. The infra-littoral zone which is an algal dominated zone, extends from the end of the inter-tidal zone down to the lowest limit, where sea grasses and photophilic (light-loving) algae can live. In clear seas the lower limit of this zone can extend up to a depth of 50 meters. Apart from the unicellular and multicellular floating algal forms (phytoplankton) that exist in this zone, some of the large photophilic macroalgae that grow in  this region are the brown algae Cystoseira, Dictyopteris and Sargassum and the green algae Dascycladus. A lot of microhabitats are created within these  algal beds, that support a rich fauna and flora, that include invertebrates and fishes. Among the invertebrates are burrowing and sessile organisms such as sponges, and bivalve mollusks, and burrowing and creeping organisms such as gastropod mollusks, the bailer volute being one of them. Swimming animals such as fishes and copepods feed, shelter and lay their eggs in the algal beds.

The circa-littoral zone

The region beyond the infra-littoral zone is known as the circa-littoral zone that extends from the lower limit of the infra-littoral down to the maximum depth where multicellular photosynthetic forms can exist, which is about 200 meters in depth. At such depths the light intensity is very low, and therefore vegetation is sparse consisting of foliose red algae in the shallower areas and crustose red algae in the deeper areas. Some of the crustose red algae species found are calcified Lithothamnia and non-calcified Cruoria. The circa-littoral zone is dominated by animals of the burrowing, sessile and mobile forms. The sessile attached forms include the tubeworms, bryozoans,  sea mats, sponges, corals and sea fans. The burrowing forms include heart urchins and the gastropod mollusks. Animals that live on the surface include brittle stars and sea cucumbers, and animals that are partly embedded in the sediment are sea pens and soft corals. Among the prominent mobile organisms in this zone are the decapod crustaceans, echinoderms, mollusks and fishes. The small mobile organisms include the isopods, amphipods, nemerteans and polychaetes. The sea-snail bailer volute also exists in this zone in the shallower areas less, than 100 meters, and remains burrowed just below the surface during the daytime.

Feeding and Reproduction

The bailer volute usually remains buried in the sandy or muddy bottom of the sea and come out at night to feed. They are carnivorous, feeding on other predatory gastropods, such as Hemifusus tuba and Babylonia lutosa and the dog conch, Strombus canarium.

Volutes have a limited location and distribution, because of their breeding habits. They do not produce free swimming larvae known as veligers that swim and float over a vast area of the ocean, such as in oysters and clams, and colonize new areas. The sexes are separate in the volute sea-snails, but external differentiation of male and females are difficult, except perhaps for the difference in sizes. The males have a single testis where the sperms arise, and are conducted along a coiled vas deferens to the penis. The females have a single ovary producing eggs, which are conducted along the oviduct to the pallial oviduct, where the eggs are fertilized by the sperms introduced by the male. Most gastropods show a courtship behavior before copulation. The fertilized eggs are covered with albumen produced by the albumen gland, and then jelly produced by the capsule gland. The fertilized eggs surrounded by a gelatinous capsule pass down the remaining part of the oviduct, and are laid through the genital pore. The eggs remain attached together as a gelatinous mass, before they hatch into tiny young snails, which look like adults in all respects. The young snails are on their own until they develop into adults, provided they are lucky enough to escape from other predatory gastropods.

The Description of the Shell

The average length of a Melo melo snail shell is between 150 mm (15 cm) to 275 mm (27.5 cm), with a reported record size of 362 mm (36.2 cm). The color of the shell varies from beige to orange, with a smooth outer surface showing distinguishable growth lines. Sometimes  the shell has dark brown bands while others are without any distinct markings. The interior of the shell is glossy cream, becoming light yellow near its margin. The shell has a wide aperture, nearly as long as the shell itself, a feature that facilitates its use to bail out water, like a wide-mouthed container.

The large fleshy foot of the snail is brown in color with white stripes like a zebra. Hence the name zebra sea snail. The white stripes are also found on the long siphon. These features are characteristic of the Melo melo volute.

Shell of melo-melo sea snail

Shell of melo-melo sea snail

Photo Above Creative Commons

The Uses of Bailer Volutes

1) Source of Food - Bailer volutes had been put to multiple uses by man since very ancient times. One of the first uses of bailer volutes for ancient man was as a source of food, like all other marine mollusks such as oysters, clams, and other marine gastropods. The Melo melo sea snail is still used as a delicacy in countries of Southeast Asia, such as Vietnam and China.

2) Container for bailing water from boats - Another ancient use of the bailer volute, was the use of its large shell with a wide aperture as a container for bailing water out of their boats by ancient people like the aborigines of Australia, from which the shell derives its name.

3) Used as bowls - The aborigines used bailer shells also as bowls in the kitchen, and for holding liquids like vegetable oils.

4) Used as a scoop in the markets - The shells are also used as scoops for salt, sugar and flower in the local markets, in the regions where they are found.

5) Used as pots for ornamental plants - Another novel use for the big shells was as flower pots for ornamental plants.

6) Used as horns in religious ceremonies and rites - In Myanmar (Burma), melo shells were sometimes used as horns, like the conch shells, and blown at religious ceremonies, or while performing religious rites at the Buddhist temples.

7) Used as ashtrays - In the coastal villages of Burma, the melo shells are commonly used as ashtrays for cheroots and cigars.

8) Collectors' value - Shells of the family volutidae are popular collectors items because of their decorative nature, and therefore highly valued by shell collectors. The bailer volute shell is also valued because of its rarity.

9) Source of non-nacreous pearls - The Melo melo sea-snails produce one of the rarest, largest and most spherical natural pearls in the world, with a fiery orange color. Melo melo pearls were known in Southeast Asia since ancient times, the pearl being used as a symbol of expression of various virtues, such as a symbol of perfection in Buddhist thought, as the pearl requires no enhancement or alteration by man, when it emerges.

10) Melo pearls were used as marbles - In Burma, where very few people knew about the value of these pearls, young children played marbles with these pearls in the days of ignorance.

History of the usage and appreciation of melo-melo pearls

The melo-melo pearl became a symbol of perfection in Buddhist thought

The existence of melo-melo pearls originating from the bailer volute had been known and appreciated by ancient cultures and civilization of the Southeast Asian nations, such as China, Vietnam, Cambodia, Japan etc. The perfectly round fiery orange pearl, with its shimmering flame structure, naturally beautiful, a gift of nature, that did not require man's intervention, became closely associated with the Buddhist philosophy, that had very large following in this region. The pearl became a symbol of perfection in Buddhist thought, and became one of the eight precious emblems of the Buddha. Both the bailer volute shell and the pearl became objects of veneration by Buddhists.

The dragon and flaming-pearl motif became a favorite motif of emperors symbolizing the emperor striving to achieve the noble virtue of perfection.

The ancient Chinese, Japanese and Vietnamese believed that pearls were created from droplets that fell from the dragon in the heavens, on the sea, that were taken in by the open shells of clams, oysters and sea-snails. These droplets of water from the heavens grew into pearls, nourished by the moonbeams that fell on the seas at night time. Thus, the fiery melo-melo pearl with a flaming tail and the dragon, became a ubiquitous motif of the decorative arts of the Chinese and Vietnamese, appearing in paintings, textiles and ceramics. The dragon in these artistic expressions symbolized the emperor, who was shown pursuing the pearl, the symbol of perfection, a goal that every emperor strived to achieve. Thus the dragon and flaming- pearl motif became a favorite motif of the emperors, which was used freely in all artistic expressions and even on the imperial robes. The melo-melo pearls being sacred objects, were never drilled or strung as beads, but preserved as objects of devotion. The Emperors of Vietnam valued the pearl so highly that they send their ships to search for these rare beauties in the waters of the Halong Bay and the South China Sea.

Chinese Dragon and Flaming Pearl Motif on a banner

Chinese Dragon and Flaming Pearl Motif on a banner

The Rarity of Melo Melo Pearls

Melo-Melo pearls are rare but precise figures of their frequency of occurrence not available

Melo melo pearls are one of the rarest natural pearls in the world. Gem-quality purple quahog pearls are believed to be the rarest natural pearls in the world, whose probability of occurrence had been calculated to be around 1 in 2 million. Please go to the following webpage for the computation of the probability of quahog pearls :- The Golash quahog pearl brooch - the Pearl of Venus. Melo melo pearls are less rarer than purple quahog pearls. However, computing an approximate probability for the pearls occurrence is difficult because of the lack of statistics. Recently, after extensive trawler harvesting of the Melo melo sea-snail in the South China Sea off the coast of Vietnam,  as a source of food not mainly for the Vietnamese markets, but for export to China, significant quantities of the rare pearl appeared as a by product of the industry. However, no precise figures were given for the frequency of occurrence of melo-melo pearls in these waters. Sea-snail fisherman gave a vague figure of one in several thousand for these pearls.

Melo-Melo pearls were once extremely rare not because of their rarity of occurrence inside the snails, but because of the difficulty of their harvesting from the deep waters of the ocean

For quahog pearls the frequency of occurrence of a purple pearl was given as one in 100,000, out of which only one in 20 was said to be of gem-quality, giving a probability of 1/100,000 x 1/20 = 1/2,000,000. This is an extremely rare occurrence, and purple quahog pearls are considered to be the rarest of all natural pearls. In the case of melo-melo pearls the pearls were once extremely rare not because of the rarity of their occurrence inside the snails, but because of the difficulty in harvesting the sea-snails from the deep waters of the ocean, which was sometimes as deep as 70-100 meters. The countries of Southeast Asia did not have the technology to harvest sea-snails at such depths.

Melo-Melo pearls were largely unknown to the west until recently. G.F. Kunz's "The Book of the Pearl" published in 1908, had no reference to the pearl

Thus, the beautiful melo-melo pearls largely remained unknown to the west in ancient times and until the recent past. Even George Frederick Kunz's famous publication of 1908, "The Book of the Pearl" the most authoritative book on the subject of pearls for a long period, had no reference to the rare melo-melo pearls of Southeast Asia !

In Burma, at one time children played marbles with melo-melo pearls, showing the pearls were not so scarce at that time

In Burma, in the coastal villages, where originally only a few people knew about the value of melo-melo pearls, children used these pearls to play marbles. The fact that the pearls were used as marbles by children perhaps gives an indication of their availability at one time in Burma, and shows that melo-melo pearls were not so scarce at that time.

An episode in Vietnam that lends strong evidence for the extreme rarity of melo-melo pearls - the story of the cook who processed and cooked sea-snails for almost fifty years but never found a melo-melo pearl

In May/June 2009 GIA Field Gemologists Vincent Pardieu and his companions Jean Baptiste Senoble and Kham Vannaxay of France, Lou Pierre Bryl of Canada and David Bright of USA, undertook a GIA Laboratory Field Trip to Vietnam in order to visit and collect specimens from mines in Vietnam, producing ruby, sapphire and spinel. During this trip they also took the opportunity to visit the most important melo-melo pearl trading center in Vietnam, the Cat Ba Island in North Vietnam, to which all trawlers fishing the Melo melo sea-snail from all around Vietnam headed, to dispose of their catches. Dealers in Cat Ba purchased the harvest of sea-snails from the fisherman, which were later exported to China, where there was a great demand for its meat.

While at Cat Ba, Vincent Pardieu and his companions visited the port area and the sea front where many hotels. restaurants and tourist shops were located. They found that only one restaurant in Cat Ba offered melo sea-snail dishes in its menu, and a live sea-snail was kept in a fish tank at the entrance to the restaurant. The owner cum cook of the restaurant offered to cook the sea-snail for the visitors with green bananas and spices, which they accepted. The visitors made friends with the cook, and explained to him the purpose of their visit. The cook who had been in the business for nearly fifty years, cooking thousands of melo sea-snails during his life time, was surprised to hear that there were occasional pearls inside the sea-snail. He confessed that during this long period of handling and cleaning sea-snails he had never come across a pearl inside any snail. In fact the cook said that this was the first time he was hearing that there could be rare and valuable pearls inside these snails. If what the cook had told the field gemologists from the GIA  was the real fact, which obviously is the case, as there was no reason for him to hide the fact that he had discovered a melo-melo pearl from the sea-snails, the story lends strong evidence for the extreme rarity of these pearls.

Mr Duc, the former Vietnamese navy diver who during his lifetime had seen thousands of Melo melo sea-snails but only one melo-melo pearl, another indication of their true rarity.

While at Cat Ba, Vincent Pardieu and his companions also met Mr. Duc a Vietnamese man in his fifties who was a former navy diver, who said that his friend Mr. Tchi, a local fisherman discovered a beautiful melo-melo pearl in 1994, from a sea-snail which he collected, near Trin Hu, Virgin Island, while he was working as a diver in Ha Long Bay. Mr. Tchi found two large melo snails in the shallow waters of the Ha Long Bay, closer to the shoreline. The two of them were surprised by the size of the sea-snails, which Mr. Duc said was as big as his hat and weighed around 8 kg, too big for the area where they were discovered, where melo sea-snails were usually quite small. Mr. Tchi then went about cleaning the sea-snails before cooking them, when  yet another shock greeted them. A large stunningly beautiful orange round pearl suddenly appeared from inside the contents of the snail. Mr. Duc said that the pearl was about 2 cm (20 mm) in diameter, and was glowing, a clear reference to its flame structure. He said that Mr. Tchi kept the pearl with him, but was not sure whether he still had the pearl. He further said, that he never saw or heard about any other melo pearl in Ha Long Bay, during the six years he served as diver, and since his retirement in 2002. Mr. Duc as a diver had seen thousands of Melo melo snails, but in his lifetime had seen only one melo-melo pearl. This gives an indication as to the true rarity of melo-melo pearls.

The large scale harvesting of Melo melo sea-snails in Vietnam begins in the early 1990s, leading to a significant increase in the availability of melo-melo pearls in the international pearl markets

In the early 1990s the Vietnamese began intensive harvesting of Melo melo sea-snails using trawlers and dredgers, around the snail-rich waters of the Spartly and Paracel archipelagos in the South China Sea, the Back Long Vi Island in the Ha Long Bay, and the Phu Quoc Island near the Cambodian border. The dredges used by trawlers are bottom-towed gear, consisting of a metal frame with a blade or teeth to dig into the sediment and extract the shelled mollusks, and a mesh bag to collect the catch. Hydraulic dredges that shoots jets of water, onto the seabed to lift out the target species have also been developed. Even though the use of dredges had facilitated access to sea-snails living 70-100 meters in the sub-littoral zone, their use had caused considerable damage to the benthic zone, such as changes in structure, nature and chemical composition of the substrate, and the de-stabilization of the benthic eco-system.

The intensive trawler fishing of sea-snails in the 1990s and later from 2000 to 2009, had resulted in a considerable increase in the availability of melo-melo pearls originating from Vietnam, in the pearl markets of the world. However, marine biologists have expressed the view that continued intensive trawler fishing, causing damage to the sea-snails ecosystem, would decrease recruitment, and drastically deplete sea-snail resources, rendering future exploitation totally uneconomical and unsustainable. This seems to have happened already, as reflected both by decreased harvests and the decrease in size of the sea-snails caught. The average life span of a melo-melo sea-snail is not known exactly, but believed to be several decades. Thus even if there is sufficient recruitment, for snail populations to reach normal levels and sizes would take several decades.   

How melo-melo pearls are formed ?

The formation of the pearl is a natural reaction to the lodging of an irritant in the mantle tissues

Non-nacreous melo-melo pearls are formed in a manner similar to pearl formation in other shelled-mollusks such as oysters, mussels and clams. The formation of the pearl is essentially a reaction to the entry of an irritant into the mantle tissues, or an internal organ such as the gonads of a shelled-mollusk. The irritant can be a parasite, damaging debris or waste material. According to the Gemological Institute of America, the very rare melo-melo pearl is most likely the result of an intruder. The shell's wide aperture, nearly as long as the shell itself, may perhaps facilitate the entry of the irritant, which eventually lodges itself in the mantle tissues of the snail. The mantle is responsible for the creation, maintenance, coloration and modification of the gastropod shell. The shell forming substances such as conchiolin and calcium carbonate are secreted by the cells of the mantle. The same substances are laid around the irritant to form the pearl. However, the crystalline form of calcium carbonate that is incorporated in the pearl is mainly calcite and not aragonite. The calcite microcrystals are laid as needles and do not scatter light waves like aragonite platelets. Hence the lack of iridescence in these pearls. The calcite microcrystalline needles are associated to form bundles of fibers, whose arrangement and alignment causes a type of chatoyancy known as "flame structure."

The size and age of the pearl is related to the size and age of the snail

The pigment secreting cells in the mantle that was responsible for the coloring of the shell, also secretes the same pigments that are incorporated into the conchiolin (protein) layers of the pearl. It appears that the size and color of the melo-melo pearl is determined by the size and the lip color of the parent sea-snail. A frequent observation that has been made is that the largest melo-melo pearls usually appear in the largest sea-snails. This is clearly linked to the age of the snail, an older snail being fully developed is much larger than a younger snail which is not fully developed. Likewise the chances of a pearl growing inside an older snail being fully developed is much greater than a pearl growing inside a younger snail. Thus the age of the pearl is related to the age of the snail. Therefore, some of the large melo-melo pearls that have been discovered from very large snails, must be as old as the snail themselves, which necessarily means they are several decades old.

The site of development of large perfectly spherical melo-melo pearls are the soft tissues of the mantle and the visceral mass

Another interesting feature that has been observed in many melo-melo pearls, apart from their extraordinary sizes, is their perfectly round or spherical shape, the most desired shape for pearls. For a pearl to develop into a perfect sphere, its development has to take place in a fairly soft tissue, where equal resistance is offered to the expanding pearl from all sides. If the resistance offered on one side is greater than the other sides, the resulting pearl could acquire any shape other than spherical, such as near-round, oval, drop-shape, baroque etc. Except for the muscular foot which is quite tough, other parts of the snails body, such as the visceral mass and the mantle, situated inside the shell are soft, and may provide the ideal location for the development of spherical pearls.

Characteristics of melo melo pearls

The melo-melo pearls with a combination of desirable characteristics, such as the intense orange color,  spherical shape, unique flame structure, porcellaneous luster, durability and above all their natural provenance, has become one of the rarest and most sought after pearls in the world today. The following is an account of the natural characteristics of these pearls considered under different sub-headings.

1) Non-nacreous pearls:- Melo-Melo pearls are non-nacreous pearls like conch pearls and are also produced by a marine gastropod like conch pearls. However the families to which the gastropods belong are different. While the Melo melo sea-snail belong to the Volutidae, the Strombus gigas sea-snail that produces conch pearls belong to the Strombidae. Likewise the habitat in which the two snails are found are also different. While the natural habitat of the Melo melo sea-snail is the Indo-Pacific region, the natural habitat of the Strombus gigas sea-snail is the tropical zone of the Western Atlantic Ocean from Bermuda to Brazil, that also includes the Caribbean and the Gulf of Mexico.

2) Luster :- Being non-nacreous melo-melo pearls do not have the luster and iridescence of nacreous pearls. But, they still have a porcelain-like luster, which is known as a "porcellaneous luster." Both the lack of iridescence and brilliant luster are associated with the type of crystalline calcium carbonate deposited, and the structure and arrangement of the calcium carbonate microcrystalline units.

3) Flame Structure :- As if to compensate for the lack of luster and iridescence nature has gifted melo-melo pearls with another unique and attractive feature, known as the "flame structure," whose presence gives a fiery flame-like shimmering appearance to these pearls, particularly to the orange variety of the pearl. This spectacular "flame structure" sometimes surpasses the beauty of most low-quality nacreous pearls. The flame structure is also associated with the arrangement of the microcrystalline calcium carbonate fibers, similar to the "chatoyancy" in beryls and other gemstones caused by rutile fibers.

4) Color :- The colors of melo-melo pearls is related to the color of the shells. The shell color of the bailer volute varies from beige (pale-sandy color) to orange,  and brown. The interior of the shell is yellow to cream color. Thus the pearls produced by the bailer volute can have three basic colors  yellow, orange, and brown  or different shades of these colors or a mixture of two of these colors, such as light, medium and dark yellow; light, medium and dark orange; light, medium and dark brown; light, medium and dark yellowish-orange and orangish-yellow; light, medium and dark yellowish-brown (tan) and brownish-yellow; light, medium and dark orangish-brown and brownish-orange. The commonest and most-beautiful colors are the different shades of orange. White is also a very rare color in which melo-melo pearls sometimes appear. Another very rare color that has been reported is reddish-orange.

The pigments or biochromes associated with these colors are secreted by special secretory cells in the mantle tissue. The color of melo-melo pearls like the conch pearls are affected by ultra-violet radiation, and jewelry set with such pearls are ideally suited for evening wear.

5) Shape :- Melo-Melo pearls occur in a range of shapes, such as spherical or round, near-spherical or near -round, oval or egg-shaped, and baroque or irregular shape. The commonest shape in melo-melo pearls are spherical and near-spherical, although perfectly spherical shapes may be extremely rare.

6) Size :-  The size of melo-melo pearls varies with its age and is closely related to the size of the shell from which it was derived. Usually larger shells that are older produce larger pearls. The size of the pearls can vary from a few millimeters to around 35 mm. The largest pearl on record, which has the size of a ping-pong ball, has a size of 37.58 mm to 37.97 mm along different diameters, and has a record weight of 397.52 carats. In keeping with a size of a few mm to around 35 mm, the weight of melo-melo pearls also vary from a few carats to over 300 carats.

7) Hardness :- The hardness of melo-melo pearls is approximately 5 on the Mohs scale. This compares with a hardness of  2.5 to 4.5 for natural nacreous pearls. Thus melo-melo pearls are harder than other natural pearls

8) Refractive Index :- the refractive index of melo-melo pearls vary from 1.51 to 1.64

9) Natural Provenance :-All melo-melo pearls are necessarily natural in origin. This is obviously because all attempts to culture these rare beauties have so far proved unsuccessful.

10) Effect of u-v rays on the color of melo-melo pearls :- The color of melo-melo pearls like all other organic gems are affected by ultra-violet radiation, and jewelry set with such pearls are ideally suited for evening wear. However such effects become apparent only after prolonged exposure over many years. The fading of color is caused by the destruction of color causing pigments by u-v rays in sunlight. The color of conch pearls are also affected by u-v radiation. Even black Tahitian pearls can be affected, as reported by G. F. Kunz in his book "The Book of the Pearl" in reference to a black pearl that lost its color and luster after exposure to sunlight in a jeweler's shop window.

The surge in popularity of melo-melo pearls

The recent worldwide popularity of melo-melo pearls attributed to the efforts of Benjamin Zucker, the New York gem dealer and writer

Although melo-melo pearls had been known and appreciated in Southeast Asia from time immemorial, its sudden worldwide popularity is of recent origin, attributed to a New York gem dealer and writer Benjamin Zucker. The intensive trawler harvesting of Melo melo sea-snails began in early 1990s, and significant quantities of melo-melo pearls were discovered from the sea-snails. In 1993, a collection of 23 deep-orange melo-melo pearls,  perhaps purchased by a Swiss dealer from the Vietnamese was shown to Benjamin Zucker for assessment and evaluation. In fact the dealer is reported to have left the pearls with Zucker for further intensive studies. Zucker got in contact with his friend Kenneth Scarratt, of the Gemological Institute of America, who later became the Director of the GIA in Bangkok. Scarratt with his vast knowledge and experience  with pearls of all kinds, and author of the book "Pearl and the Dragon" the first extensive gemological report on melo-melo pearls, identified the pearls immediately as Vietnamese in origin. Zucker who was also a pearl enthusiast, and was interested in finding out more about these rare beauties, got together a small team of gemologists, scholars and writers, who visited Vietnam, with a view of documenting all available facts about these pearls, including their origin and the habitat of the mollusks in which they develop. Zucker's historic visit to Vietnam was the inspiration for a 1997 article on melo-melo pearls in the Smithsonian magazine, which gave a big boost to the popularity of these pearls.

Record price set by a fiery orange melo-melo pearl at a Christie's auction in Hong Kong in November 1999

It is believed that Zucker's explorations in Vietnam and the subsequent Smithsonian article, set the stage for the record price registered for a melo-melo pearl at a Christie's auction in Hong Kong in November 1999. The near-spherical fiery orange pearl with dimensions of 23.0 x 19.35 mm, fetched a record price for a single pearl, USD 488,311. The pre-sale estimate of the pearl was placed only between USD 20,000 - 30,000. The unexpected strong bidding for the pearl resulted in a hammer price 16 times higher than the upper pre-sale estimate, a trend that was attributed to Zucker's  work on the pearl.

A second melo-melo pearl sold by Christie's Hong Kong in April 2000 realizes a lower but still attractive price

In April 2000, Christie's of Hong Kong put up another near-spherical and fiery orange melo-melo pearl for sale. The pearl was larger (31.70 x 31.26 mm) and more beautiful than the pearl that set the price record in November, 2009. Accordingly, in keeping with the prices realized at the first auction, the auction house placed a higher pre-sale estimate of USD 150,000 to 200,000 on the pearl. However, the price realized at the auction was USD 277,272, higher than the upper pre-sale estimate, by USD 77,272.

The after-effects of the two record-breaking auctions of melo-melo pearls

Attempts to increase production of melo-melo pearls to cash in on their popularity

The extraordinary prices recorded by two melo-melo pearls at Christie's auctions held in Hong Kong, in the years 1999 and 2000, was good news for the Vietnamese pearl prospectors, and all other countries in the Indo-Pacific where the Melo melo sea-snail was found and harvested. In Vietnam, the exploitation of the Melo melo sea-snail continued with renewed vigor resulting in a considerable increase in production of melo-melo pearls. Burma, Thailand and Cambodia took a keen interest in taking a fresh look at their sea-snail resources. In Burma fishing trawlers known as "Wa-lat" or "Gar" began extensive exploration of the muddy bottom of the seas at depths of 30m to 50 m, along the Arakan coast and in the southern region of Dawei (Tavoy) , the Mergui Archipelago, and Kawthaung in the Andaman Sea, near Thailand. The result was significant quantities of melo-melo pearls entering the pearl markets. In Thailand Melo-melo sea-snails were being harvested as a by product of the crab-fishing  from the Gulf of Thailand. However, the production of melo-melo pearls was not significant.

The entry of melo-melo pearls from old collections into the markets

. Apart from that melo-melo pearls held in private collections in Asia made their appearance in the pearl markets. The owners of these collections were keen on cashing in on this unexpected boom in prices. The result was a glut of melo-meo pearls in the markets of all sizes, shapes and colors, but not necessarily of the highest quality. The ultimate result of this chain reaction was a depression in prices, from hundreds of thousands to tens of thousands of dollars

The enhanced prices for melo-melo pearls gave a boost for research activities in culturing these rare and unique fireballs of nature

The incentive provided by enhanced prices for melo-melo pearls was so great, that countries began investing heavily on research for the culturing of Melo melo sea-snails and melo-melo pearls. One of the pioneers in this research  was Suraphol Chunhabundit, marine biologist at the Chulalongkorn University in Bangkok, working at the Sichang Marine Science Research and Training Station in the Chonburi Province in the Gulf of Thailand. It is reported that he had achieved partial success in culturing melo-melo pearls by implanting  Pigtoe mussel nuclei into sea-snails. However, details of his research has not been published, and the research was still continuing when funding for his project was terminated abruptly. Efforts in culturing not only melo-melo pearls inside the Melo melo sea-snail, but also conch pearls inside Stombus gigas had met with limited success in other parts of the world. The primary reason for this failure is the difficulty in accessing the pearl-producing area of the snail for implantation due to the peculiar anatomy of the univalve gastropods.

Marketing of melo-melo pearls

Apart from the regular auctions held by two of the most prominent international auction houses, Christie's and Sotheby's in Hong Kong, where top-quality melo-melo pearls sometimes appear, and fetch quite attractive prices, melo-melo pearls produced in Southeast Asia,  also eventually find their way to another regional marketing center for all types of gemstones. viz. Bangkok in Thailand, where these rare beauties are auctioned regularly and go to the highest bidder.

The future of the melo-melo pearl ?

Vietnam is the main producer of melo-melo pearls in the world today, followed by Burma. The exploitation of melo-melo sea-snails with renewed vigor, following the popularity of melo-melo pearls, is undoubtedly going to have a serious impact on their populations. It is reported that already in Vietnam the snails are becoming scarcer and smaller in size. This is the obvious result, due to the long life-span of the snails, and the reduction in the recruitment of young snails. Recruitment declines when the adult populations are drastically reduced by over fishing. Even if there was adequate recruitment, if sufficient time is not given for the snails to reach their maximum size and potentialities, the size of the snails caught will necessarily be small, and any pearl developing inside will also be small, as it is an observed fact, that the size of the pearl depends on the size of the snail. Thus, if exploitation of sea-snail resources are not carried out in a planned and methodical way, giving sufficient time for adult populations to re-establish themselves, the future of the natural melo-melo pearl industry will be very bleak indeed! The pearls will get scarcer and dearer and eventually disappear altogether from the pearl markets of the world.

This was exactly what happened to the natural pearl industries in Venezuela, Columbia and Panama during Spanish colonization of these countries. Pearls that were discovered by Christopher Columbus towards the end of the 15th-century was totally exploited and exhausted in about 150 years, and the industry abandoned in the mid-17th century. Another instance from history comes from the Gulf of Mannar, in Sri Lanka (Ceylon), one of the most ancient sources of natural pearls in the world, where sustainable exploitation using traditional methods continued for over 2,000 years, without any depletion of resources, but after colonization by the Portuguese (1505-1656), Dutch (1656-1796) and the British (1796-1948), and the intensive exploitation that followed, destroyed the natural pearl industry in 1906, never to recover again, the final death blow being given by Mikimoto.

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Related :-

1) Queen Mary Conch Pearl Brooch

2) Susan Hendrickson's Conch Pearls

External Links :- 

1) Melos and their Pearls in Vietnam - May/June 2009- Concise Field Report, Volume 2, Part 1. Vincent Pardieu, GIA Laboratory, Bangkok.

References :-

1) Melo Pearl - by David Federman,

2) Pearl That Really Aren't - The Conch and the Melo Melo "Pearl" - by Amy Hourigan, Graduate Pearls Program, GIA.

3) Lot 2390 - An Impressive Melo Pearl, The Dragons Flaming Pearl - Bonhams & Butterfields auction 2005.

4) Melo Pearls From Myanmar - Han Htun, Bill Larson, Jo Ellen Cole

5) Report on cultivation of Melo melo pearls in Thailand, September 2001 - www.parels-ael

6) Nature and Importance of Circalittoral Faunal Turfs (CFTs) -

7) Marine Habitats - Malta Environment and Planning Authority -

8) Littoral Zone - From Wikipedia, the free encyclopedia

9) Gastropoda -

10)The Pearl Book - Natural, Cultured & Imitation Pearls - Terminology & Classification - CIBJO, The World Jewelry Confederation.

11) Melo melo - From Wikipedia, the free encyclopedia

12) Baler Volute, Melo melo, Family Volutidae - Wild Fact Sheets.

13) Melos and their Pearls in Vietnam - May/June 2009- Concise Field Report, Volume 2, Part 1. Vincent Pardieu, GIA Laboratory, Bangkok

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