Conch Pearl Gemstone & Information | Gemopedia by JTV | Gemopedia™
A conch is a marine gastropod or, more simply, a large sea snail. Conchs are valued for their meat, shell and non-nacreous pearls. Conch pearls are formed by concentric layers of fibrous calcium. This layering often produces a much-desired flame structure, which is characteristic of conch pearls. Because they are a calcareous concretion, the pearls have a porcelain finish and luster, very similar to the interior of the conch shell. Conch pearls are not cultured, but are usually found as a by-product as fishermen clean their catch for conch meat. The gems are usually baroque or oval in shape and generally a salmon-colored orange-pink.
Beige, Ivory, White, Brown, Mottled Coloring Pink, Yellow, Orange, Red
Conch-pearl classificationCommonNameConch PearlSpeciesNAVarietyConch PearlColorsBeige, Ivory, White, Brown, Mottled Coloring Pink, Yellow, Orange, RedAlternateNamesGemstoneGroupsKeySeparationsRI, birefringence blink, magnification and appearanceClassificationCommentsUse birefringence blink method to obtain birefringence. Misnomer: Nassau pearls. Conch pearls are not considered true pearls. They come from the giant conch Strombus gigas. Color may fade if pearl is exposed to sunlight for long periods of time.
Conch-pearl chemistry & crystallographyChemicalNamecalcium carbonate, conchiolin and waterChemicalFormulaCaCO3 with H2O and other organic materialsSynthesisCrystalSystemNAChemistryClassificationCarbonateNatureNaturalCrystallinityNon-CrystallineChemistryComments
Conch-pearl optical propertiesTransparencyTranslucent - OpaqueDispersionOpticalCommentsRefractiveIndex1.53-1.685Birefringence0.155OpticCharacterOpticSignPolariscopeReactionAggregate (AGG)FluorescenceSWUV: Variable
Conch-pearl characteristic physical propertiesHardness2.5-4CharacteristicCommentsStreakSpecificGravity2.83-2.87 Typical:2.85ToughnessFairInclusionsConch pearls have a flame like structure and does not have nacre but a porcelain like finish.LusterDullStabilityPoorFractureUnevenCleavageNone