By Iris Stratman
The Intrigue of Phenomenal Properties
There is special kind of wonder to be found in light distortions. From kaleidoscopes to phantasmagoria theater, manipulations of light are timeless and have an intrinsic draw that delight viewers. This play-of-light is prevalent in gemstones, specifically those of the phenomenal variety. Phenomenal gemstones are defined by their unique ability to distort light, creating an otherworldly optical effect. In the coming weeks, there will be more fun tidbits about the various kinds of gems that possess these qualities such as moonstones, abalone pearls, and cat’s-eye. You perhaps have even seen them before in the gallery! I thoroughly enjoyed learning all about how these stunning optical effects are created. There is plethora of unique properties that result in the ethereal beauty of a phenomenal stone.
When light is broken up into different colors, it is called iridescence. Akin to soap bubbles, oil slicks, and butterfly wings, this rainbow effect is found in gems such as opals, abalone shells, and labradorite.
Notably found in moonstones among other gems, this property is defined by its milky, semi-opaque luster. Adularescence is caused by the parallel layers of albite in a stone’s structure. We can thank adularescence for the soft, celestial glow of moonstones, quartz, and many others! Ceylon and rainbow moonstones are both present in Eve’s “Angel” ring, from her “Medieval” series.
Named after aventurine quartz, this stunning coruscate effect is the result of small, thin inclusions within the stone. When light hits it, the gem can look like tinsel preserved in crystal! In sunstones, aventurescence is cause by flecks of copper, known as schiller, growing simultaneously within the stone. A perfect example of this is shown in the sunstone located in the center of “The Hidden Dream” ring from Eve’s “No Forwarding Address” series.
The six-rayed star within the center sapphire of Eve’s “Interchange” ring is a prime example of asterism. This property occurs in minerals that contain small, fiber-like crystal inclusions. Stones such as rubies and sapphires that feature asterism are cut into a cabochon. When direct light hits the cabochon-cut gem, a star shines out from within its core!
What makes cat’s-eye so unique is its glowing band. With a cabochon cut, these parallel needlelike inclusions in the stone imitate the look of an actual eye of a cat! However, this property is not limited to solely cat’s-eye and tiger’s-eye stones. You can see chatoyancy prevalent in other precious gems, such as moonstones, or the chrysoberyl centered in Eve’s “The Auspices Have Spoken” ring.
In the case of labradorescence, the importance of the schiller effect cannot be emphasized enough. The schiller effect occurs when light scatters around within thin layers of feldspar, resulting in a distinct play-of-color known as labradorescence. As the name implies, this optical treat is notably found in labradorite.
It is said that you can see the universe inside of a precious opal. Indeed, the rich swirls of color that are formed from hardened silica spheres do recall those of nebulas. In opals, the diameter, uniformity, and overall alignment of the silica spheres and their arrangement results in the play-of-color. This quality is especially prominent in black opals which are the most highly valued of all. The play-of-color is put into action when lighting and perspective is changed. When the orientation is switched, new colors emerge from within. Notice the galaxy of color and light play in the 144.3 carat koroit opal featured in Eve’s “Le radeau de la meduse” pin.