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Opals & Gemstones

What’s the Difference Between a Precious and Non-Precious Opal?

The word opal notoriously conjures images of rainbows and colorful flashes. But not all opal aligns with this visual; it speaks to precious opal, but largely neglects non-precious opal which accounts for a great deal of the opal recovered from mining.

Opal is formed from a solution of silicon dioxide and water. As rainwater trickles down through the fissures in the earth it picks up silica from sandstone along the way. Next, the now silica-rich solution settles into cracks and voids of all sizes. Over a long period of time the water evaporates and leaves behind a beautiful silica deposit we call opal.

Opal is composed of uniform spheres of silica, which assemble in a grid-like structure. The spaces between these spheres contain the silica solution. As light passes through the spheres and into this silica solution, it is diffracted, producing an alluring rainbow of vibrant hues.

Both precious and non-precious opal is mined from these crevices and while both are quite beautiful, they are very different from one another.

Light Diffraction Through Silica Spheres
Light Diffraction Through Silica Spheres, Image by Open Australia

Precious vs. non-precious opal

Precious opal is the term used for any opal that exhibits a “play-of-color” or iridescence. This means as light illuminates the inner contours of the opal, it’s diffused or dispersed throughout the silica spheres to create a brilliant prism of spectacular color. Other examples of things that exhibit this play-of-color or iridescence are soap bubbles, feathers, butterfly wings, and seashell nacre. 

If you’ve been following NIXIN Jewelry for a while, you may recall our email about the Papilio Blumei Ring, inspired by an Indonesian butterfly, that described this precise effect. If you'd like to join our mailing list, add your email address to the bottom of our homepage.

Papilio Blumei Ring from NIXIN
Papilio Blumei Ring by NIXIN

Non-precious opal, also called common or “potch” opal, does not exhibit a play-of-color like precious opal and is often milky in appearance. Common opal is typically gray, black, white, or amber in color, but it also occurs naturally in a variety of beautiful colors including a range of lovely pastels. Non-precious opal is found in the same environments as precious opal but is considered less valuable. Depending on the appearance of the potch, a miner or cutter may opt to use it, given the beautifully unique patterns that can result when potch is woven into precious opal, as in the example below.

Boulder Opal with Caramel Colored Potch
Boulder Opal with Caramel Colored Potch

Precious Opal, Image by James St. John

How is opal valued?

It is notoriously difficult to value opals because there are so many factors to consider, and they vary so widely in appearance and quality. There are three main aspects that determine whether an opal is precious (highly valuable) or non-precious (less valuable):

  • Color
    Body tone (color) is one of the most important factors in the classification and valuation of opals and refers to its overall background or underlying color. Black opal, white opal, crystal opal, boulder opal and matrix opal are all varieties of precious opal, which is also called noble opal. Generally, opals with darker backgrounds are more valuable than those with a lighter background because stones with darker backgrounds offer a more vibrant display or play of colors. Under the right circumstances, the color red, a rarer find, can also drive up the value of an opal.
  • Pattern
    Distinct color that is displayed in a pattern or pattern segments further determines the quality of an opal. Excellent pattern types include uniform color segments, straight edges, large sections of color in a random pattern, parallel cascading lines of narrow, rolling color or thin strips of overlapping color that may or may not resemble an object, landscape, animal, or person.
  • Clarity
    The size and quantity of inclusions (small imperfections) can detract from the value of an opal. Imperfections may include cracks, grains of sand or other minerals, potch lines, webbing (gray lines), and windows (sections without color).

Sometimes, potch can even “paint” incredible pictures within an otherwise precious opal, blurring the lines between what’s deemed valuable by traditional industry standards and what is viewed as a treasure in the eye of the beholder.  Here at NIXIN, we readily embrace a combination of qualities in these sublime stones, as long as the final result is uniquely beautiful.

Lightening Ridge Black Crystal Opal Necklace
Lightening Ridge Black Crystal Opal Necklace by NIXIN

NIXIN Jewelry curates an extraordinary selection of opals to offer the most stunning, collection of handcrafted Australian opal rings for women. We offer a variety of sizes and styles so you’re sure to find one that takes your breath away. Shop our precious opal ring collection, and don’t forget to explore our equally spellbinding necklaces and earrings.

It’s time to get lost in a galaxy of brilliant colors.

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How Is Opal Formed?

Have you ever wondered about the science behind the splendor? How those incredible shifting rainbows are created inside of stone? Opals are formed from a mineral known as silica, specifically hydrated amorphous silica. Silica is a common mineral found in soil, sand, granite, concrete, rock, and many other natural materials. Hydrated amorphous silica simply means that opal has a high water content.

Opal is found in many places like Brazil, Mexico, Honduras, and the Western US, however Australia produces 95% of the world’s precious opal. NIXIN Jewelry sources nearly all of our precious opal from Australia, working with material like boulder opal from Winton, Queensland to crystal opal from famed Lightning Ridge and from Coober Pedy, the Opal Capital of the World.

How does opal form?

Opal is found deep in the Earth’s crust near faults, cracks, or fissures. It is believed that around 30 million years ago a large amount of silica was released and filled in these cracks. In fact, fossil evidence suggests that Australia used to be under the ocean. Some of those fossils were replaced by silica and formed what we call Shell Opal and Opalized Belemnites (ancient squid-like creatures).

Image of opalized belemnite
Opalized Belemnite, Photo by James St. John

Like ocean water, rainwater also contains small amounts of silica (among other minerals) and collects more as it falls onto soil, sand, granite, and concrete. Over time the silica, which has a spherical chemical structure, settles into perfectly stacked spheres along these fissures. This symmetrical, three-dimensional array creates diffraction and interference, which is what produces the brilliant opal colors we all know and love. The range of colors depends on the size of the silica spheres as well as the refraction at the surface of the opal. A mere 1cm of opal can take up to 6 million years to form; though slow to grow, the resulting myriad of colors is breathtaking.

Aquanova Opal RingMoondust Diamond and Lightning Ridge Crystal Opal RingAlchemy Opal Ring

How is opal mined?

While a range of mining methods are employed, much opal is mined by shaft sinking or shaft mining, which means a vertical tunnel is excavated from the top down until some promising “opal dirt” is discovered. Once opal is discovered, a miner then slowly branches out sideways using a hand pick or screwdriver to carefully extract any opal they found. Opals are delicate gemstones, and should be handled with care from extraction and transporting to designing and wearing, but when cared for properly, they can last a lifetime.

NIXIN Jewelry has relationships with opal suppliers across the globe, working directly with the miners who extract this spectacular material from the earth, as well as with the talented artisans who cut these beautiful gems, revealing the colorful secrets within. When you purchase opal jewelry from NIXIN Jewelry, you can feel confident knowing you are supporting a network of small businesses and skilled artisans around the world who love what they do.

If you’re looking for a one-of-a-kind piece of art that evokes emotion and tells your unique story of strength, perseverance, or love let NIXIN Jewelry guide you through our selection of precious opal rings for women. Nicki, Founder and Designer of NIXIN Jewelry, selects only the most striking opal gemstones and transforms them into spellbinding visuals meant to awaken your soul. Each opal ring is dressed in 14K gold and paired with carefully curated precious gemstones like diamonds, sapphires, and emeralds that echo the translucent shades of the opal.

NIXIN Jewelry offers a stunning, bespoke collection of handcrafted Australian opal rings, necklaces and earrings in an array of sizes and styles.

Visit our shop to start living your life—in color.

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