Tridacna Pearls Gemstone & Information | Gemopedia by JTV | Gemopedia™
Tridacna pearls form within the tridacna clam, commonly known as the "giant clam." These large mollusks grow in the warm coral reefs of the Indo-Pacific Ocean, living up to 100 years and reaching sizes of up to 47 inches across. Understandably, the largest pearl of any kind on record is a tridacna pearl weighing 6.4 kilograms. These non-nacreous pearls have a porcelain-like white surface.
Tridacna-pearls classificationCommonNameTridacna PearlsSpeciesNAVarietyTridacna PearlsColorsYellowish WhiteAlternateNamesGemstoneGroupsKeySeparationsRI, birefringence blink, magnification and appearance.ClassificationCommentsUse birefringence blink method to obtain birefringence. Tridacna pearls are not a true pearls, they come from the giant clam. They range in size from 1 cm to very large. Misnomer: coconut pearl.
Tridacna-pearls chemistry & crystallographyChemicalNamecalcium carbonate, conchiolin and waterChemicalFormulaCaCO3 with H2O and other organic materialsSynthesisCrystalSystemNAChemistryClassificationCarbonateNatureNaturalCrystallinityAggregateChemistryComments
Tridacna-pearls optical propertiesTransparencyTranslucent To OpaqueDispersionOpticalCommentsRefractiveIndex1.53-1.685Birefringence0.155OpticCharacterOpticSignPolariscopeReactionAggregate (AGG)FluorescenceSWUV: Variable
Tridacna-pearls characteristic physical propertiesHardness2.5-4CharacteristicCommentsStreakSpecificGravity2.83-2.87 Typical: 2.85ToughnessFairInclusionsTridacna pearls have a yellow to white porcelain appearance with flame like structure.LusterDullStabilityPoorFractureUnevenCleavageNone