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Chatoyant chrysoberyl


#1

Thanks for the compliment on my colored stone articles in Bench
magazine!

Just as in other chatoyant materials, chatoyant chrysoberyl (true
"Cat’s eye" or cymophane) owes it’s chatoyancy to the
crystallographic orientation of fine needle-like inclusions, in this
case, usually rutile or a closely related-mineral. The finer the the
"needles" the less coarse the “cat’s eye”. The finest material
simply glows and appears as a lenticular “eye” opening and closing
as the stone is rotated. The cab must be cut with the base parallel
to the dirction of the fibers or needles, and a higher dome will
produce a more pronounced eye than a lower dome. The colors range
from a yellow to brown to yellow-brown or yellow-green, just like
transparent chrysoberyl. And, yes, there is a color change variety,
the alexandrite cat’s eye. As you might guess they are rare and
COSTLY.

Chrysoberyl presents no challenges to the bench worker…it is
very, very hard, very tough and fairly heat resistant, but too much
heat will affect the rutile inclusions. The ultrasonic should be
just fine, and while many have experienced no problems doing a QUICK
tip repair with the stone in place, in my shop, all expensive or
hard-to-replace stones are removed from the setting for repair work
involving the torch. Hope that answers your question!

Wayne Emery
The Gemcutter