Body Tone & Brightness of Opal

Opal is a truly unique gemstone, like a work of art, famous for its ever-changing play of color. But did you know that an opal’s body tone and brightness play a huge role in determining its value? These factors help classify opals into different categories, from black opals to light opals, each with distinct characteristics. Let’s break it all down so you can better understand what makes an opal truly shine.

What is Opal Body Tone?

Body tone refers to the background color of an opal, ranging from pitch-black to milky white. The darker the body tone, the more the colors can stand out. This is why black opals from Lightning Ridge are considered the crème de la crème of the opal world.

Black opals have the darkest body tone and are the most sought-after due to their intense color contrast. While many assume that the darkest tone has the highest value factor, that’s not necessarily true. A black opal with the deepest body tone but weak color doesn’t necessarily hold a higher value than a slightly lighter tone black opal with a vivid brightness. 

Dark opals sit between black and light opals, with a body tone that is neither fully black nor white. Their value largely depends on color brightness rather than its tone. A high-brightness dark opal can rival a subdued black opal in price if its colors are vivid and strong.

Crystal opals are a semi-transparent type of opal, meaning when held up to a light source, distorted images and light can be seen through the gemstone. They sit on the lighter end of the body tone scale, and because of their glassy transparency mixed with a deep play-of-color and at times, a vivid brightness, crystal opals are the closest rival in value and quality to black opal.

White opals tend to have the palest body tones. Light opal can still exhibit bright colors; however, because their tone is lighter, the colors may not always pop as much as they do in black, dark opal or crystal opals. 

What is Opal Brightness?

Brightness measures how vibrantly an opal’s colors shine when exposed to light. It ranges from B1 (subdued) to B5 (vivid). Even within the same body tone category, brightness can significantly alter value, just like other opal value factors like colors and patterns. For example, a black opal with a vivid B5 brightness could be the determining factor that makes it more valuable than a black opal with the brightness of a moderately bright B2.

A great example is an opal with deep red hues. Red is the rarest and most valuable opal color, so even if an opal has a lower brightness level, strong red flashes can still drive up its value.

When evaluating an opal, consider both its body tone and brightness. While a darker background can enhance the color contrast, the brightness can make an opal truly vibrant.