Sapphire (Synthetic Star) Gemstone & Information | Gemopedia by JTV | Gemopedia™
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.
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 classificationCommonNameSapphire (Synthetic Star)SpeciesCorundumVarietyFlame-Fusion Synthetic Star SapphireColorsLight To Dark Violet, Bluish Violet, Blue To Greenish Blue, Brown, Gray, White; All Colors Other Than Blue Need To Be Designated By ColorAlternateNamesLab Created Star SapphireGemstoneGroupsKeySeparationsMagnification, appearance and RIClassificationCommentsStones typically have flat bases and are well cut calibrated cabochons. Stones will have brighter colors than natural sapphire.
Sapphire-synthetic-star chemistry & crystallographyChemicalNamealuminum oxideChemicalFormulaAl2O3Synthesisflame fusionCrystalSystemTrigonalChemistryClassificationOxideNatureSyntheticCrystallinityCrystallineChemistryComments
Sapphire-synthetic-star optical propertiesTransparencySemitransparent - OpaqueDispersionStrength: weak fire Value: 0.018OpticalCommentsRefractiveIndex1.762-1.77
Tolerance:(+0.009/-0.005)Birefringence0.008-0.01OpticCharacterUniaxialOpticSignNegativePolariscopeReactionDoubly Refractive (DR)FluorescenceSWUV: inert to moderate chalky blue to yellowish green
Sapphire-synthetic-star characteristic physical propertiesHardness9CharacteristicCommentsStreakWhiteSpecificGravity4.1-3.95 Typical:4ToughnessExcellentInclusionsFlame 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.LusterSubAdamantineStabilityVery GoodFractureConchoidalCleavageNone