Sapphire (Synthetic Star) Gemstone & Information | Gemopedia by JTV | Gemopedia™

Sapphire (Synthetic Star)

Synthetic star sapphire exhibits the optical phenomenon called asterism, a star-like pattern created on the surface of a gemstone when light encounters parallel fibrous, or needle-like, inclusions within its crystal structure. Light that strikes the inclusions within the gem reflects off of the inclusions, creating a narrow band of light. When two or more intersecting bands appear, a star pattern is formed. The flame fusion process for creating gems, also called the Verneuil process, is the most affordable and common synthesis method for producing corundum (ruby and sapphire) and spinel. Powdered chemicals (the building blocks of the gem) are dropped through a high-temperature flame. The molten powder repeatedly falls from the flame onto a rotating pedestal, creating a synthetic crystal, called a boule, which can later be faceted into a gemstone. Synthetic gems have the same chemical, optical, and physical properties of their natural counterparts, but are a more cost-effective alternative to a natural gem.

Colors

Light To Dark Violet, Bluish Violet, Blue To Greenish Blue, Brown, Gray, White; All Colors Other Than Blue Need To Be Designated By Color

  • Sapphire-synthetic-star classification

    CommonName
    Sapphire (Synthetic Star)
    Species
    Corundum
    Variety
    Flame-Fusion Synthetic Star Sapphire
    Colors
    Light To Dark Violet, Bluish Violet, Blue To Greenish Blue, Brown, Gray, White; All Colors Other Than Blue Need To Be Designated By Color
    AlternateNames
    Lab Created Star Sapphire
    GemstoneGroups
    KeySeparations
    Magnification, appearance and RI
    ClassificationComments
    Stones typically have flat bases and are well cut calibrated cabochons. Stones will have brighter colors than natural sapphire.
  • Sapphire-synthetic-star chemistry & crystallography

    ChemicalName
    aluminum oxide
    ChemicalFormula
    Al2O3
    Synthesis
    flame fusion
    CrystalSystem
    Trigonal
    ChemistryClassification
    Oxide
    Nature
    Synthetic
    Crystallinity
    Crystalline
    ChemistryComments
  • Sapphire-synthetic-star optical properties

    Transparency
    Semitransparent - Opaque
    Dispersion
    Strength: weak fire Value: 0.018
    OpticalComments
    RefractiveIndex
    1.762-1.77
    Tolerance:(+0.009/-0.005)
    Birefringence
    0.008-0.01
    OpticCharacter
    Uniaxial
    OpticSign
    Negative
    PolariscopeReaction
    Doubly Refractive (DR)
    Fluorescence
    SWUV: inert to moderate chalky blue to yellowish green
    LWUV: Inert
    CCFReaction
    Pleochroism
    Unobservable
  • Sapphire-synthetic-star characteristic physical properties

    Hardness
    9
    CharacteristicComments
    Streak
    White
    SpecificGravity
    4.1-3.95 Typical:4
    Toughness
    Excellent
    Inclusions
    Flame fusion stones might display curved growth and a unusually display a centered and well defined 6-rayed star. The curved growth is especially visible on the flat base of the stone. The stones might have gas bubbles and minute rutile needles that make up the star will confined to the surface of the stones.
    Luster
    SubAdamantine
    Stability
    Very Good
    Fracture
    Conchoidal
    Cleavage
    None