Birthstone Spotlight: Opal
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It’s time for our birthstone spotlight for October! Can you believe it’s October already? This month, we will learn about opals!
What is Opal?
Opal originates in the ground as the result of seasonal rain. In certain regions with dry ground (such as Australia’s outback), rain soaked deep into the ancient rock underneath the ground. This rainwater carried dissolved silica with it. When the water dried up, these deposits of silica were left behind, forming opal.Opals are generally classified into two broad categories: precious and common. Precious opal displays opal’s unique rainbow color (called play-of-color), while common opal does not.
Opal can be found in many locations throughout the world, but Australia’s fields are the most abundant sources. Some other significant sources of opal include Ethiopia, Mexico, and Brazil. Deposits have been found in many different places, as well, including the US, Central Europe, Honduras, Indonesia, Madagascar, Peru, and Turkey.
The History of Opal
Like many gemstones, opals have been beloved for thousands of years. To ancient Romans, opals were a symbol of hope and love. They gave it the name opalus, which means “precious stone.” Throughout history, many cultures have attributed special powers to opals. For example, ancient Greeks thought opals could guard people against disease and grant them the gift of prophecy.Quality Factors
Opal has unique quality factors compared to other gemstones. The three main quality factors for opals are color, pattern, and clarity. Examining the quality of an opal involves fives steps:- Determining the type of opal
- Determining the opal’s play-of-color in ratio to its background color
- Determining the opal’s transparency
- Determining the opal’s clarity
- Evaluating the opal’s cut for symmetry, crazing, pits, or other clarity marks
Opal’s colors have a wide spectrum. There are black opals, white opals, and fire opals. White opals are the most common. With most other quality factors being equal, black opals will usually demand a higher price than white opals.
Fire opals are often yellow, red, or orange and are generally somewhere between transparent and translucent. You may hear these called “Mexican opals” or “Mexican fire opals.”
The clarity for opals depends on the type of opal being examined. Like diamonds, opal clarity is higher the fewer inclusions the gemstone has. However, unlike diamonds, transparency is a clarity factor for opals. Higher transparency is desirable in some types of opals, while in others (such as black opals), an opaque background is considered better.
How to Care For Opal Jewelry
Opals are one of the more delicate gemstones, so they should be handled with care. The best and safest way to clean an opal is with warm, soapy water. Opal is a mostly stable gemstone, but try to avoid exposing your opal jewelry to high heat or sudden temperature changes, as it may fracture.Interesting Facts About Opal
- Opal is October’s birthstone, as well as the gemstone for the 14th anniversary.
- Opal ranks as a 5.5 to 6.5 on the Mohs scale.
- Opals were once thought to bring their wearers good luck and have been credited with numerous supernatural origins and powers.
- Opals gained a reputation for being unlucky from Sir Walter Scott's 1829 book, Anne of Geierstein.
- The most expensive opal (per gram) in the world is known as “Virgin Rainbow” and is valued at $750,000!
