Cutting Star and Cat’s Eye Gems

Chrysoberyl - cat's eye gems
“Chrysoberyl Cat’s Eye,” 3.28 cts, with “milk and honey” effect. © All That Glitters. Used with permission.

Well-cut star and cat’s eye gems are a delight to the eye and great fun to cut. These phenomenal stones display asterism and chatoyancy, respectively. Both effects are the result of light reflecting off inclusions within the gemstones. Although silk (fine included crystals) is the most common cause of these visual phenomena, any inclusions that reflect light in parallel lines can create these displays, including hollow tubes, feathers, and veils.

Silk, Tubes, Veils - star and cat's eye gems
Inclusions that can cause star or cat’s eye gems include silk (left), hollow tubes (center), and veils (right).

How many times have you seen off-color, faceted sapphires caused by gold rutile inclusions clouding the interior? Many of these would have produced a nearly transparent star stone if properly oriented. The star versions are worth more and are a lot …

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