Opal is known for its unique ability to diffract light into a blaze of flashing rainbow colors called play-of-color, which caused writers, for centuries, to compare opals to lightning, volcanoes, galaxies, and fireworks. Opals are classified in a couple different ways. The first is based on whether or not they display play-of-color. In this system opals either display play-of-color (precious opals) or they do not (common opals). Gem experts have another way of categorizing opal using other physical characteristics.
- White Opal is the most common, possessing a translucent to semi-translucent white or light gray body color. They also display play-of-color.
- Black Opal is translucent to opaque, shows a black or other dark body color and flashes play-of-color. “Black opal’ does not mean the stone’s background color can only be black, it simply means the stone has a dark tone, such as dark blue, gray, or black. Black opals are much rarer and highly prized than white opals.
- Fire opal’s body color is normally transparent to translucent yellow, orange, or red and often doesn’t show play-of-color.
- Boulder and matrix opal consists of gemstones which retain part of the boulder it forms in, known as matrix, on the back of a thin piece of colorful opal.
- Crystal opal is transparent to semitransparent with a clear background and shows exceptional play-of-color. It is the second most popular opal, behind only black opal.
- Water opal is normally colorless, but can also show faint tints of bluish grey, green or yellow with a transparent to translucent gelatinous appearance similar to glass. Water opal may or may not display play-of-color.
I am a great fan of opal, particularly black opals. I have very little experience designing jewelry featuring opals which display play-of-color, so I rely on experts in opal jewelry design to create the pieces I may offer through Gordon’s Curated Selections.
Opal is an October birthstone. To learn more about opal, any of our other gemstones or how to care for or clean jewelry visit our education and resources page.