Coral (Proteinaceous) Gemstone & Information | Gemopedia by JTV | Gemopedia™
Coral has been prized throughout history for its natural beauty. Like pearl, coral is also an organic gem consisting of more than 90% calcium carbonate. All coral consists of the remains of skeleton-like support structures that were built by colonies of very small marine animals, known as coral polyps.
Black, Dark Brown, Golden, Yellow, Blue
Coral-proteinaceous classificationCommonNameCoral (Proteinaceous)SpeciesNAVarietyColorsBlack, Dark Brown, Golden, Yellow, BlueAlternateNamesBlack Coral, Golden Coral, King's Coral, Akori CoralGemstoneGroupsKeySeparationsRI, appearance and magnificationClassificationCommentsBlack to dark brown=King's coralYellow to brownish yellow=golden coral sometimes bleached black coral. light to medium dark blue=Akori coral
Coral-proteinaceous chemistry & crystallographyChemicalNameChemicalFormulaC32H48N2O11SynthesisCrystalSystemNAChemistryClassificationOrganicNatureNaturalCrystallinityNon-CrystallineChemistryComments
Coral-proteinaceous optical propertiesTransparencySemitranslucent - OpaqueDispersionOpticalCommentsRefractiveIndex1.56-1.57
Tolerance:(+0.010/-0.010)BirefringenceOpticCharacterOpticSignPolariscopeReactionAggregate (AGG)FluorescenceSWUV: inert
Coral-proteinaceous characteristic physical propertiesHardness3CharacteristicCommentsStreakSpecificGravity1.3-2.12 Typical:1.35ToughnessGoodInclusionsIn cross section conchiolin coral has a tree ring like growth structure with concentric and circular rings. Sometimes the rings will look like white crescents. The surface of the branch will have a bumpy appearance. Black coral is sometimes bleached to look like golden coral and will visually appear to have a rougher texture.LusterVitreousStabilityFractureConchoidal, UnevenCleavageNone