A star stone is a gemstone which has been cut and polished in a way which takes advantages of natural inclusions in the stone which create a very distinctive star pattern when light reflects from the stone. Many star stones are sapphires, although rubies and many quartzes can be turned into star stones as well. These stones have historically been viewed with intense superstition, and they have also been highly prized, thanks to their rarity.
In order for a stone to be polished into a star stone, it must have a unique set of inclusions which are sometimes referred to as “needles” because of their fineness. Such inclusions can ruin a stone, depending on how it is handled and polished, and star stones require special care during the polishing process to ensure that they come out well. When the stone is polished properly and placed in the light, the inclusions catch the light and reflect it, creating a brilliantly rayed star.
Star stones are always cut in cabochon shape, meaning that they are cut and polished flat, not faceted. Cabochons typically have a flat back to make them easier to set. One of the most famous star stones is the Star of Bombay, a massive cabochon which was once owned by actress Mary Pickford. The stone is currently on display in the Smithsonian Museum, if you are interested in seeing a first rate example of a star stone.
The property which star stones exhibit is known as asterism. Asterism can take a number of forms, from a single line streaked across a stone to a complex pattern with a multitude of rays. As a star stone is brought into the light and moved, the pattern of the reflection will change, causing the star to slowly cross the stone. The distinctive rayed pattern will also be tinged with the deep colors and hues of the stone.
Because star stones are so distinctive and stunning on their own, most of them are set in very simple settings which emphasize the star design. The settings are designed so that they do not obscure the pattern of the star, and if other stones are used in the setting, they are usually modest, so that they do not distract from the focal point of the piece. Many star stones are quite large, making them suitable for necklaces, brooches, and heavy bracelets.
