Chrysoberyl
The name Chrysoberyl is derived from the Greek words 'Chrysos' & 'Berullos' meaning 'Golden Crystal'. Although the name refers to the golden yellow colour, it also occurs in a lighter yellow and shades of green and brown.
Chatoyant material is cut as a cabochon (en-cabochon) to display a fine cats eye effect. The term Cat's Eye, without reference to a particular gemstone name,is used to indicate that the gemstone is a chrysoberyl. Other cat's eye gemstones are named, for example, cat's eye quartz, cat's eye tourmaline etc.
Cat's eye is the most precious of all chatoyant gemstones, it has a sharper eye than that of other chatoyant stones. The inclusions that cause the eye effect are very fine oriented needles of rutile or other minerals.
Alexandrite is a colour change variety of chrysoberyl.
Properties of the Gemstone and Additional Information
| Gemstone type: | Chrysoberyl |
| Crystal System: | Orthorhombic |
| Chemical Composition: | Beryllium Aluminium Oxide, BeAl2O4 |
| Colour: | Yellow, golden yellow, green and brown. Alexandrite is a colour change stone, showing green in sunlight (daylight) and red in incandescent light and candle light. |
| Lustre: | Bright vitreous |
| Pleochroism: | Trichroic, strong in dark stones, weak in light stones. |
| Dispersion: | Low |
| Hardness: | 8 1/2 on the Mohs' scale |
| Toughness: | Excellent |
| Cleavage: | Indistinct |
| Density in gm/cc: | 3.70 to3.78 |
| Double refraction: | Yes |
| Refractive index: | 1.74 to 1.76 |
Common Treatments
Chrysoberyl is not normally treated, but cat's eye is often imitated by cat's eye quartz and other chatoyant materials.