CLARITY

So, price is one indication of what you are buying. In any case, in buying cat's-eyes, be sure to know what the gem is, in order to get the best gem for the money.

Tigereyes are related to cat's-eyes. Both have the same chatoyancy, but the visual effect is different. Tigereyes have alternating bands of yellow and brown, not a single slit. They belong to the quartz family and are relatively common and inexpensive.

*Star rubies and star sapphires have inclusions that create a silky sheen and a specific effect. Whereas in cat's-eyes, the needle-like inclusions occur in only one direction, in star gems the inclusions form three intersecting lines for a star effect. The star effect is called asterism and may occur in other gems as well.

Inclusions, therefore, may even be a reason for a gem's desirability. The fact that opalescence, chatoyancy, and asterism are inclusions, nevertheless, means that these gems are polished to show off their uniqueness rather than cut in facets or faces in the wav diamonds and non-star rubies and sapphires are cut to show or their brilliance.