Coral (Proteinaceous) Gemstone & Information | Gemopedia by JTV | Gemopedia™

Coral (Proteinaceous)

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.

Colors

Black, Dark Brown, Golden, Yellow, Blue

  • Coral-proteinaceous classification

    CommonName
    Coral (Proteinaceous)
    Species
    NA
    Variety
    Colors
    Black, Dark Brown, Golden, Yellow, Blue
    AlternateNames
    Black Coral, Golden Coral, King's Coral, Akori Coral
    GemstoneGroups
    KeySeparations
    RI, appearance and magnification
    ClassificationComments
    Black 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 & crystallography

    ChemicalName
    ChemicalFormula
    C32H48N2O11
    Synthesis
    CrystalSystem
    NA
    ChemistryClassification
    Organic
    Nature
    Natural
    Crystallinity
    Non-Crystalline
    ChemistryComments
  • Coral-proteinaceous optical properties

    Transparency
    Semitranslucent - Opaque
    Dispersion
    OpticalComments
    RefractiveIndex
    1.56-1.57
    Tolerance:(+0.010/-0.010)
    Birefringence
    OpticCharacter
    OpticSign
    PolariscopeReaction
    Aggregate (AGG)
    Fluorescence
    SWUV: inert
    LWUV: inert
    CCFReaction
    Pleochroism
    None
  • Coral-proteinaceous characteristic physical properties

    Hardness
    3
    CharacteristicComments
    Streak
    SpecificGravity
    1.3-2.12 Typical:1.35
    Toughness
    Good
    Inclusions
    In 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.
    Luster
    Vitreous
    Stability
    Fracture
    Conchoidal, Uneven
    Cleavage
    None