What Color is Opal?

What Color is OpalIf you love opal stones, chances are your birth month is October. Or, you’ve developed an appreciation for the unique and colorful radiance of opals.

What makes opals so special? Well, just one opal stone can encompass a spectrum of colors, all shining in an eye-catching, opalescent glow that’s entirely unique to opals.

You might be wondering why opals are so colorful and exactly what color they are. There are several factors that contribute to the unique rainbow of colors that an opal stone emits. However, to fully explain this natural wonder we first need to define some scientific terms.

Don’t worry, we won’t get too technical, but we will include just enough information to help you fully grasp what processes cause opals to have such colorful diversity.

What is an Opal?

An opal is an amorphous, or shapeless, stone made up of silica. The structure inside an opal stone contains tiny organized spheres, each lined in a consistent and organized arrangement. When light directly passes through these spheres and comes into contact with the silica, the light bends and emits a variety of colors.

Opals are the birthstone of October, and signify hope, purity and good fortune. These stunning stones are famous for their “play of color,” because they can quickly shift from light, incandescent colors to intense and bright fiery colors.

By definition, the word “opal” means to see a change in color. Below we’ll outline the science and terminology explaining why opal stones change colors so much.
What Color is Opal

What is Diffraction?

When light breaks into a series of bands, they can either emit light, dark or colored bands. With opals, diffraction creates a broad spectrum of vivid colors ranging from pale grays to intense blues and fiery reds.

What is Deflection?

When light passes through an object and bends, it changes course from a direct or straight line. Deflection influences the visible light spectrum, allowing our eyes to see the complex array of opalescent colors radiating from an opal stone.

What is Opalescence?

Few stones have a dedicated term to describe their unique appearance. Part of what makes opals so special is their opalescence. In short, opalescence relates to the optical effect garnered from the unique arrangement of features an opal has: gleam, color, sheen, glow and iridescence. The terms opalescence and iridescence are used interchangeably, however the former is directly attributed to the opal stone.  

How Deflection and Diffraction Influence the Color of Opals

The size of the spheres inside the structure of an opal stone will influence which colors are visible to us. The light passing through an opal stone is first deflected, or bent, then diffracted, or broken up, and finally colors are emitted from the light rays in the stone. The reason opal appears iridescent and multi-colored is because when the stone is moved, light will hit different spheres at different angles within the stone, radiating a variety of unique colors. In this way, opals appear to be constantly changing and shifting their coloring.

Due to this factor, calling an opal one singular color is not necessarily easy as they contain multiple colors. No matter which way you tilt or shift an opal stone, it’ll reflect different colors each time. This is why opals make such attractive jewelry stones. While single color stones might pair well with a selection of colors, opals pull colors from every space in the rainbow, making them great statement pieces.
What Color is Opal

Other Factors That Affect Opal Color

Just as the different angles you hold an opal will reveal different colors, the size of the stone will also dictate the color. That’s why it’s so difficult to define opal as a singular color. However, there are some rules of thumb.

  • Large opal stones in round and oval shapes will reveal warm red tones.
  • Small opal stones will be cool, emitting predominantly blue and green tones.
  • Stones that are intensely colored are a clue that the silica structure within the stone is uniform.

Types of Opals

As you’ve gathered by now, pinpointing one color to describe the vast array of colors within an opal stone is a difficult task. However, there are common categories of opals. Here’s a look at some of the popular and unique opal stones available:

  • White opals have a white, milk-toned base color while still emitting a gorgeous pastel spectrum of color.
  • Black opals have a dark base and predominantly reflect blue, green and gray tones.
  • Fire opals contain sparks of intense fiery colors including red, orange and yellow.
  • Crystal opals are virtually transparent, and reflect bright and clearly defined colors.
  • Blue Opals range from light grey to aqua and turquoise to deep blue, and feature streaks of sandy, orange and milky colored earth tones.
  • Pink Opals are a peach, salmon hue and are speckled with black and deep orange.
  • Crystal Opals are crystal opals that are a rough formation with bright, neon colors.
  • Tricolor opals are extremely rare and appear predominantly silver or pink with a soft, satin finish. The coloring of these unique opals emulate the look of frozen ice.

How Are Opals Used in Jewelry?

Raw opal stones make unique decorations that are perfect for jewelry. Opals make beautiful necklace pendants, ring center stones and accent stones, necklaces and earrings. The wonderful thing about opals is that they come in a variety of shapes and colors, meaning you can customize your jewelry and have a wide range of styles to choose from.
What Color is Opal

Opals are often cut into unique shapes including hearts, triangles, rectangles and even the shape of animals like dolphins and turtles. Jewelers will even splice opals with other stones like lapis lazuli and labradorite to create a unique, colorful piece.

Whether worn as a matching earring set, a unique gemstone pendant or sparkling ring, opals are one of nature’s most eclectic and unique gifts. If you want to encapsulate the vivid spectrum of the rainbow into one stone, opals are the perfect choice.


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