Chrysoberyl cat’s eye is a gemstone quality variety of beryllium aluminum oxide which exhibits a rare optical trait known as ‘chatoyancy’. Chatoyancy is the unique ability to reflect light in a way that resembles the slit eye of a cat, hence the name ‘cat’s eye’. Chrysoberyl is considered the ‘original’ cat’s eye gem, and is in fact the only gem that can be traded as simply ‘cat’s eye’; all other varieties must be traded using very specific names, such as ‘cat’s eye quartz’ or ‘cat’s eye apatite’. Unlike most other cat’s eyes, chrysoberyl can exhibit very sharp and distinct eyes under almost any kind of light, which makes it extremely attractive and desirable, especially combined with its superior level of hardness and durability.
The chrysoberyl species was first discovered in 1789 by renowned geologist, Abraham Gottlob Werner. For many years, it was referred to as simply ‘chrysolite’, but today, the term is no longer commonly used. Despite its descriptive name, chrysoberyl is not actually a beryl, which is aluminum beryllium silicate, whereas chrysoberyl is beryllium aluminum oxide. Some forms of chrysoberyl may exhibit the unique ability to change color under different lighting sources; these are known in the trade as ‘alexandrite’. Color change chrysoberyl is considered to be one of rarest and most valuable gems today.
Chrysoberyl cat’s eye is typically found in shades of lemon and lime, ranging from greenish yellow to light honey. It can also occur in attractive shades of mint-green to darker brownish-green. Typically, lighter, golden colored stones are considered most desirable.
Chrysoberyl cat’s eye is often translucent to opaque, owing to the presence of natural needle-like inclusions. However, in most cases, since the inclusions are responsible for the desirable cat’s eye effect, the reduced level of transparency does not affect the stone’s overall value. Cat’s eye chrysoberyl typically has an attractive vitreous luster.
Chrysoberyl cat’s eye is always cut in cabochon in order to maximize the desirable chatoyancy. They are most often finished in oval, round or pear shapes, as these shapes tend to preserve the most rough carat weight. Calibrated gemstones are available, but will typically command higher premiums. Most cat’s eye chrysoberyl gemstones are ‘native cut’ and often feature ‘uneven bottoms’. For this gem type, uneven bottoms are quite acceptable, because in order to center the cat’s eye, cuts necessitate unevenness.
Chrysoberyl is a very rare mineral and gemstone quality deposits of cat’s eye are even rarer. Most chrysoberyl cat’s eye is sourced from Brazil, China, India, Sri Lanka and Zimbabwe. Some other notable sources include Burma (Myanmar), India, Tanzania, Madagascar, Pakistan, Russia and the United States.
Source: Gem Select