Color Types for Golden Sheen Sapphire
A brief description of the color types for Golden Sheen sapphire used at AGL Thai Laboratory Gemology.
From Kenya,Africa comes a new kind of sapphire. Within areas showing the golded sheen, when more in the light it has a stunning adularescence changing from deep tones to gold.
Golden Sheen Sapphire are newly discovered magnificent expression of sapphire, newer before seen in the history of gemology.
Physical Properties
Golden sheen Sapphire is a precious stone (Corundum Species)
The overall results from the 46 samples were: RI—1.76–1.77 (spot reading), birefringence—0.01, SG—3.95–4.05, UV fluorescence—inert to long- and short-wave UV radiation, and spectroscope spectrum— absorption at 450 nm and in some samples a cutoff at ~500 nm. These are typical readings for corundum.
Microscopic Characteristics
Under the gemological range clearly observed hexagonal growth patterns and color zoning in the sapphires. Furthermore, areas showing the sheen correlated numerous tiny straight needles and flakes lying within the corundum basal plane. In reflected light, the inclusions were golden metallic, and thus reflections from the inclusion created the golden sheen. In transmitted light, the inclusions appeared more orangy
brown, and under oblique illumination they exhibited various colors due to thin film interference
Further microscopic investigations, combining brightfield and darkfield illuminations, showed a correlation between the asymmetry of the dark veins and the pattern of the associated fractures.
