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STAR SAPPHIRE DOUBLE STAR 2.58 Cts NATURAL SRI LANKA LOOSE GEMSTONE - 20742
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STAR SAPPHIRE DOUBLE STAR 2.58 Cts NATURAL SRI LANKA LOOSE GEMSTONE - 20742

Product Code:20742
Availability: In Stock
  • $190.00

Carats 2.58
Size 8.2 x 7.2 mm
Color Medium Grey
Clarity TRC/SI
Shape Oval
Treatment None
Origin Sri Lanka
Location Colombo, Sri Lanka
Price $ 190.00
100% Natural - Not treated in any way.
Rare Collectors Gem
Suitable for Museums,Institutions and Students of Gemology.
Beautiful sharp Star effect.
Large Sizes are Extremely Rare!
A Gem of Lasting Beauty.
Ployasterism - Rare Multiple Starts displayed in Star Sapphires

Refractive Index: 1.759-1.778
Hardness: 9
Chemical Comp: AL2O3
Density: 4.00
Crystal Group: Hexagonal

Polyasterism is the display of more than one star within a narrow angle of observation; they aren't stars of same star-network. Rarely Sri Lankan star sapphire produce display multiple stars or polyasterism. Relatively common two-stars are often called "Siamese twins" and rare three-stars "triplets" in the trade. They not only comprise 6-ray stars but also 12-ray stars, prevalent among blue star, star ruby, and all other sapphire colors, sometimes fetching higher prices than that of single star stones. Morphological disturbances in the single crystal or forming a compound crystal by bonding/fusing/cementing several crystals together by geological reasons or Branching/penetrating of crystals are the two main causes that convert a star sapphire into a polyasteric stone. Displacement of two or more sections by glide causes display of asterism independently in the individual sections arising from their rutile needle inclusions - this is the polyasterism in single crystals. Similarly compound crystal formed by aggregation of crystals display the effect.

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