Demantoid
from the Antique Jewelry University
garnet variety was discovered in the Ural mountains. This andradite garnet which is usually bright yellowish-green is one of the highest priced gemstones one can find, especially when it has the rare and intense grass green color which rivals emerald. It has a very high brilliancy and has a high dispersion, which adds to the beauty of the hue. It has a relative high refractive index, reasonable hardness and a vitreous to adamantine luster.
The major deposits for demantoid are found in alluvial deposits in The Ural mountain range along the Bobravka River and more recently demantoid was discovered in Namibia. The superb color of the finest Russian material is the hue by which all demantoids are judged. Stones with typical and well formed horsetail inclusions are some of the most coveted gemstones.
The name of this gem means "diamond like", most probably due to its dispersive powers which actually outrank diamond but are usually surpressed by its body color.
| Gemological information for demantoid | |
|---|---|
| Color | Brownish and yellowish-green to grass green and black |
| Crystal structure | Cubic |
| Refractive index | ca. 1.89 |
| Durability | Very durable |
| Hardness | 6.5-7 |
| Family | Garnet (andradite species) |
| Similar stones | Demantoid may be confused with tsavorite garnet, peridot, emerald, diopside and tourmaline |
| Treatments | None known |
| Country of origin | Russia, Namibia |
| Demantoid care | |
| Ultrasonic cleaning | Not safe |
| Steam cleaning | Not safe |
| Warm soapy water | Safe |
| Chemical attact | Not safe |
| Light sensitivity | None |
| Heat sensitivity | Not safe |