What is Play of Color in a Gemstone?

What exactly is play of color? Is it unique to opal—and how can you tell?

This week, Justin dives into what play of color means across different gemstones, and why opal’s version is truly one of a kind.

Most gemstones get their color from trace elements. When faceted, light bounces off their surfaces and refracts through the stone, showing off that gorgeous hue. It’s a beautiful effect—but it’s not considered play of color. In fact, very few gemstones have this phenomenon.

The technical explanation? Play of color is the result of spectral colors created by the orderly arrangement of silica spheres within the structure of opal. In simpler terms: light reflects off tiny, neatly stacked silica spheres. The size of these spheres determines the color you see—reds, greens, deep blues—it’s all in the spacing. In this case, size really does matter!

When these silica spheres aren’t arranged in an orderly way, you get potch opal—an opal with a matte appearance and no play of color. Not all opals exhibit play of color. For example, Mexican fire opal often shows body tone without play of color unless it’s of gem quality. Only opals with play of color are classified as precious opals, and that’s what makes them so rare and special.

A Note on Crystal Opals

When it comes to valuing opal, things can get tricky. Sometimes, what looks like play of color might just be reflections of light—especially in polished crystal opals. These stones often reflect light through their transparent bodies, with a sparkling effect occuring when the opal has been polished on both sides. While these opals still show genuine play of color, it’s helpful to understand the distinction when assessing their value.

How Does Opal Compare to Other Gems?

Here’s where opal really shines—literally. Opal exhibits three-dimensional play of color, making it feel like you can look into the stone. In contrast, most other gemstones reflect color in a more two-dimensional way. This depth is what gives opal its soul-stirring beauty and mesmerizing presence.

This blog post and accompanying video have been fact-checked and approved by our gemologist friend Tony Smallwood—gemologist to the stars!

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