Star ruby, star sapphire, and cat’s-eye chrysoberyl are examples of gemstones that people have treasured over the ages for the fascinating changes in appearance that they exhibit. The quality of the star or cat’s-eye effect is of course an absolute requirement, but other key points in judging the quality of these gemstones are the positioning of the effect, and the gemstone’s color, transparency, and overall appearance.

The key to choosing stones with special effects is to place priority on the attractiveness of their color. Gray star sapphires, muddy red rubies, or pale yellow or dark brown cat’s eyes are unacceptable no matter how exquisite the star or cat’s-eye effect, because they will not look beautiful while they are being worn. Stones that combine good color and show a pronounced star or cat’s-eye are extremely rare and valuable. Realizing that perfect stones do not exist, emphasize color and choose a gem that you like, and enjoy the stone for the character that only it possesses.

When purchasing stones at the source, such as the mining and cutting centers of Sri Lanka or Thailand, it is important to avoid cabochons that have excessively deep or large bottoms. These stones are unnecessarily heavy and therefore relatively expensive for their face-up appearance, and they are also difficult to set into the bezels of jewelry. Purchasing such bottom-heavy stones for their low per-carat price is a prime example of being “penny-wise and pound-foolish,” and will often simply prove to be an exercise in frustration.