Organic Gems: Conch Pearls
Conch Pearl Jewelry
Source: Caribbean, Colombia, Indo-Pacific Ocean, Florida Keys
Conch pearls are far more rare than the finest natural Akoya pearl, and therefor are considerably more expensive. The name conch "pearl" is somewhat of a misnomer because these "pearls" are not nacre encrusted foreign bodies (non-nacreous) like an actual oyster pearl, but instead are calcareous concretions that form in the animal's digestive tract, in much the same way that a human kidney stone, or bezoar stone (gall stone) would.
Conch Pearls (pronounced "konk") are created in the digestive tract of spiral shelled gastropods in the Strombidae family, that live in sea-grasses or sand substrate found in warmer tropical oceans. Several conch sea-snail species produce conch pearls, and some are 'dual purpose,' producing both gems and food.
The Queen Conch (Strombus gigas Linnaeus) is the primary source for the Conch pearl. Queen Conch populations are migratory, and an adult Conch may travel within a range of 8 kilometers. Harvesting of is typically a small scale operation consiting of free-diving in waters up to 12 meters in depth.
There are no cultured equivalents for conch pearls, and these natural creations are extremely rare, taking as many as ten thousand conchs to located one conch pearl. Of those, perhaps one in ten are worthy of gem status. This may seem wastful, but because the conch is a food sourch, the discovery of a conch pearl is a bonus to the fisherman who normally hunt them.
Conch Pearl Color & 'Flame Structure'
Typical colors range from the classic magenta, pinkish-orange or salmon, to a rich brown, gold, yellow or white. The unique surface quality and chatoyancy of conch pearls is referred to as its "flame structure," describing the distinctive mottled surface pattern and characteristic flicker of light across the surface. This cloud-like flame structure pattern can sometimes take on the appearance of the iris in a human eye, and the addition of a distinct 'eye' can significantly increase the pearl's value.
Michael Zobel Conch Pearl Brooch |
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Conch Shell |
Most conch pearls have an elongated, oval, or baroque shape, and near-round specimens are very rare. Conch pearls weigh significantly more than oyster pearls, with a specific gravity of 2.85; and unlike regular pearls, are sized by carat weight. Although conch pearls can be found over 10 carats, larger sizes (above 2 carats) of conch pearls are uncommon, with the average size being under 3 millimeters in diameter. Average carat weights are from 0.2 to 0.3 carats.
Due to the high value of conch pearls, drilling and/or gluing should be avoided in the mounting, as this will devalue the pearl. Additionally, prolonged exposure to sunlight (ultraviolet light) can have a dulling and fading effect, and should be avoided.
The finest specimens come from the "queen conch" (Strombus gigas), native to the Caribbean, between South Florida (Key West, aka "Conch Republic") and the Caribbean islands of the Bahamas and Bermuda. The Strombus gigas queen conch is also commonly called caracol reina, caracol rosa, caracol rosado, caracol de pala, cobo, botuto, guarura, and pink conch.
S. gigas can grow to 12 inches in length, and is the largest mollusk native to North America. Other species that can produce conch pearls are the Horse Conch (Pleuroploca gigantea), and the Fighting Conch (Strombus pugilis) from the West Indies.
Overharvesting and pollution have greatly diminished conch populations, and as a result, fishing bans and resource management have further increased the scarcity of conch pearls. These are a collectable connoisseur's gem that can rival the intrinsic value of any faceted gemstone.
Conch Pearl Properties
The Strombus gigas Queen Conch is also harvested in the waters of San Andres, Providence and the Santa Catalina archipelago in Colombia; although overfishing has necessitated strict regulations and protection [6].
Melo Pearls
Melo pearls are another non-nacreous organic gem that is produced by the Melo melo gastropod found along the coastal areas of Myanmar (Mergui Archipelago) Cambodia, Indonesia, Thailand and Vietnam [7]. Melo pearls are known for their unusual yellowish-orange, reddish-orange, or papaya color.
Bibliography and Reference on Conch Pearls
1. Paul R. Shaffer, Rocks, Gems and Minerals  . Martin's Press
2. U.S. Fish and Wildlife, Queen Conch . www.fws.gov
3. AMNH, Queen Conch
Strombus gigas . www.amnh.org
4. U.S. Fish and Wildlife, Importing Queen Conch . www.fws.gov
5. CaracolGems, Conch Pearls . www.caracolgems.com
6. CITES, Trade in Specimens of Strombus gigas . www.cites.org
7. Jo Ellen Cole, Melo Pearls from Myanmar . www.palagems.com
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