What makes some gemstones look 'haunted'?
- Michael Fagan
- Oct 23, 2024
- 4 min read
Updated: Jul 17
With Halloween around the corner, it’s the perfect time to explore some of the most mysterious-looking gemstones in the jewelry world.
At Williamsburg Jewelers, guests are often captivated by gems that seem to glow, shimmer, or change color in ways that feel almost supernatural. Throughout history, stones with unusual visual effects have been described as magical, enchanted, or even haunted.
But while these gems may look mysterious, jewelers know the truth: it’s not magic- it’s light interacting with the unique internal structures of certain gemstones. These optical effects are known as phenomena, and they have fascinated gem collectors, artists, and jewelers for centuries. Here are some of the most intriguing phenomenal gemstone effects- and the legends that surround them.
Adularescence: the moonlit glow of moonstone
One of the most ethereal gemstone effects is adularescence, most commonly seen in moonstones. This phenomenon occurs when angled microscopic layers within semi-translucent feldspar crystals scatter light beneath the surface of the stone. The result is a soft, floating glow—often bluish or milky—that appears to drift just under the gem’s surface as it moves.
Because the effect remains visible even when the stone is carved or shaped, moonstone became a favorite of Art Nouveau jewelry designers, who loved its dreamy, mystical appearance.
The gentle glow has long been associated with lunar symbolism, giving moonstone its fitting name.
Asterism: the star hidden inside the gem
Few gemstone effects are as dramatic as asterism, the star-like pattern that appears on the surface of certain stones. This six-rayed star becomes visible only when the gemstone is cut en cabochon, meaning the stone is polished into a smooth dome rather than faceted.
The effect is created by tiny needle-like inclusions inside the stone that reflect light in intersecting directions.
Most people are familiar with star sapphires and star rubies, but the phenomenon can also appear in rarer examples of garnet, spinel, and diopside. For centuries, these star-like patterns were believed to possess protective powers, which added to their mystique.
Aventurescence: sunlight trapped in stone
Another fascinating optical effect is aventurescence, a sparkling display that resembles sunlight dancing on water. This phenomenon occurs when tiny reflective mineral inclusions scatter light throughout the stone, producing a glitter-like effect.
Aventurescence can be found in natural stones such as:
Aventurine quartz
Sunstone
It also appears in goldstone, a manmade glass material that contains reflective copper particles.
Because of their bright, lively sparkle, aventurine and sunstone have often been associated with energy, vitality, and good fortune.
Chatoyancy: the mysterious cat’s eye
The word chatoyancy comes from the French word for cat, which is fitting given the gemstone’s distinctive appearance. Stones that display chatoyancy show a narrow band of reflected light across their surface that resembles the slit pupil of a cat’s eye.
The effect occurs when light reflects from parallel needle-like inclusions within the gemstone, creating a silky band that appears to glide across the surface as the stone moves. The most famous example is cat’s eye chrysoberyl, though the effect also appears in:
Tourmaline
Quartz varieties such as tiger’s eye
Because the moving band of light seems to follow the viewer, cat’s eye gemstones have long been associated with mystery and protective symbolism.
Color change: emerald by day, ruby by night
Few gemstone phenomena are as surprising as color change.
Certain gemstones shift dramatically in color depending on the type of light shining on them. The most famous example is alexandrite, which appears green in daylight but transforms into a rich purplish-red under incandescent light.
This dramatic effect has earned alexandrite the poetic description, “Emerald by day, ruby by night.”
Natural alexandrite is extremely rare, making large stones highly valuable. Fortunately, lab-created alexandrite can display the same striking color change, allowing more people to enjoy this remarkable gemstone phenomenon.
Labradorescence: flashes of color within labradorite
Another mesmerizing effect is labradorescence, named after the feldspar gemstone labradorite. This phenomenon produces flashes of iridescent color—often blue, green, or gold—that appear to float within the stone.
High-quality labradorite from Scandinavia, known as spectrolite, can display an entire spectrum of colors and is considered particularly desirable.
More common gray labradorite still shows striking blue flashes and is widely used in jewelry such as:
Faceted gemstones
Polished cabochons
Tumbled or bead jewelry
The shifting colors give the stone a mysterious, almost cosmic appearance.
Opalescence: the dancing colors of opal
Perhaps the most famous phenomenal gemstone effect is the play of color seen in opals. As the stone moves, flashes of red, green, blue, and other colors appear to dance across its surface. This occurs because light reflects off microscopic silicon dioxide spheres arranged within the opal’s structure.
Opals have inspired myths and superstitions for centuries. At one time, some believed an opal could only be worn safely if it was received as a gift or worn by someone born in October.
Today, opals remain one of the most beloved gemstones in jewelry.
Black opals with vivid color flashes can be extremely valuable, while lighter milky opals and lab-created opals make these magical-looking gems accessible to many collectors.
Not magic—just remarkable gemstones
Although phenomenal gemstones can look mysterious, their effects are the result of natural physics and fascinating crystal structures.
Still, the visual magic they create has captivated people for centuries. At Williamsburg Jewelers, these remarkable gems continue to spark curiosity and wonder—from glowing moonstones to star sapphires and color-changing alexandrites. There may be nothing supernatural about phenomenal gemstones. But whether natural or lab-created, their dazzling effects are certainly super.
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