This is the name given to the yellow, yellow-green or grey-green variety of chrysoberyl, which displays the phenomenon of chatoyancy because of the inclusion of numerous fine, parallel crystal needles.



Appearance:
The color is greenish yellow or yellowish, sometime with a rather cold, almost grayish tone. Some fine stones are a honey brown. In the proper light, the near side will be intensified, creating a milk-and –hash honey affect. Cat’s-eye is always cut en cabochon, round or oval, to emphasize the cat’s eye effect, and can be fairly transparent. Due to its hardness, it takes and maintains good luster, and the more pronounced and pleasing the cat’s-eye effect, the greater is its value.



Distinguish features:
The most common cat’s-eye stones are the quartz, which, however, usually rather different color from chrysoberyl and are less transparent with brighter, but more superficial, chatoyancy. If there is any doubt, they can be immediately distinguish by their different density, because refractive indices are always hard to establish for curved stones.



Occurrence:
Cymophanes are mainly found in Sri Lanka and Brazil, although they are not common.



Value:
Cat’s-eye is highly priced by collectors and connoisseurs. Its value is accordingly quite high. Very fine examples are less valuable than the principal gemstones, including alexandrite, but more so, for example, than a fine topaz or spinal. Due to its value and hardness, it is also known as ‘noble cat’s-eye’.



Simulants and Synthetics:
Various natural stones have been used as substitutes, including fluorite, which, however, is much softer, and kornerpurine, are gems still rarer than cymophane, with lower hardness and density. Quartz has also been used, although its colour rarely tthat of cymophane and its density is also much lower. To our knowledge, no attempts have been made to produce this gem synthetically.