Finished version of Emerald Cut Color Change Sapphire by Daniel Stair
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Finished version of Emerald Cut Color Change Sapphire by Daniel Stair
Certified origin. Untreated material. Average brilliancy of 40 to 60%. Add to 20% or deduct to 10% for other cutting. Prices for ovals and cushions. Add 8% to 10% for rounds and pears. Add 10% to 20% for emeralds and marquis.
Heat treated material. Average brilliancy of 40% to 60%. Add to 20% or deduct to 10% for other cutting. Prices for ovals and cushions. Add 8% to 10% for rounds and pears. Add 10% to 20% for emeralds and marquis. Note: If certified Burmese and untreated, add 50%, except fair or lower grades. Typically, mid-quality untreated blue sapphire will sell for 20-30% more than a treated stone of the same quality. Top-quality unheated stones could get a premium of 50% or higher, especially if they’re large.
Average brilliancy of 30% to 40%. Add to 20% or deduct to 10% for other cutting. Prices for ovals and cushions. Add 7% to 10% for rounds, pears and marquis. Add 15% to 30% for emerald cuts.
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| Data | Value |
|---|---|
| Name | Color Change Sapphire |
| Is a Variety of | Sapphire |
| Colors | Usually, blue, bluish purple, and violet-purple. More rarely, green, yellow, and pink. |
| Hardness | 9 |
| Wearability | Excellent |
| Fracture | Conchoidal; frequent parting |
| Cleavage | None |
| Crystallography | Hexagonal (trigonal). Crystals common, often barrel-shaped, prisms with flat ends, sometimes bipyramidal; also massive, granular, in rolled pebbles. |
| Refractive Index | 1.757-1.779 |
| Birefringence | 0.008-0.009 |
| Dispersion | 0.018 |
| Luminescence | Natural color change sapphires: inert to strong red in LW, inert to moderate red to orange in SW. Synthetic color change sapphires: moderate orange to red in LW and SW, may fluoresce red in LW and mottled blue in SW. |
| Luminescence Present | Yes |
| Luminescence Type | Fluorescent, UV-Long, UV-Short, X-ray Colors |
| Absorption Spectrum | The ferric iron spectrum dominates these stones. In green and blue-green gems, rich in iron, there are lines at 4710, 4600, and 4500 in the blue-green region. Also lines at 4500 and 4600 may seem to merge and become a broad band. The three bands described are generally known as the 4500 complex and are very distinctive in sapphires. Some blue Sri Lanka sapphires also show a 6935 red fluorescent line, and the 4500 line is very weak in these gems. Synthetic color change sapphires show a line 4740. See main Sapphire gem listing for more information. |
| Pleochroism | Very pronounced. See main Sapphire gem listing. |
| Optics | RI: o = 1.757-1.770; e = 1.765-1.779 (usually 1.760, 1.768); Uniaxial (-). |
| Optic Sign | Uniaxial - |
| Luster | Vitreous to adamantine. |
| Polish Luster | Vitreous to subadamantine. |
| Fracture Luster | Vitreous. |
| Specific Gravity | 3.99-4.10; usually near 4.0. |
| Transparency | Transparent to opaque. |
| Phenomena | Asterism, color change, chatoyancy. |
| Birthstone | September |
Color change sapphires are those that change color between light sources.
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