Opulent Opals

The primary October birthstone is the glorious and magical Opal, a truly mystifying stone having a unique display of flashing rainbow colors known as play-of-color.

There are two universal classes of opal: precious (above) and common (below). Precious opal displays play-of-color; common opal does not.

Play-of-color occurs in precious opal because it’s made up of sub-microscopic spheres stacked in a grid-like pattern. As the lightwaves travel between the spheres, it diffracts light depending on the conditions under which the opal formed. This gives it the spectral colors. The rarest colors are red against black while whites and greens are the most commonly found.

Gem-quality opals fall into five main categories:

• White or light opal: Translucent to semi-translucent, with play-of-color against a white or light gray bodycolor.

• Black opal: Translucent to opaque, with play-of-color against a black or other dark bodycolor.

• Fire opal: Transparent to translucent, with brown, yellow, orange, or red bodycolor. This material—which often doesn’t show play-of-color—is also known as “Mexican opal."

• Boulder opal: Translucent to opaque, with play-of-color against a light to dark bodycolor. Fragments of the surrounding rock become part of the finished gem.

• Crystal or water opal: Transparent to semitransparent, with a clear bodycolor. Exceptional play-of-color is shown.

3.15ct Crystal Opal 

 

Other Opal Types and Treatment

Opal may be treated by impregnation with oil, wax or plastic. Opal doublets, which are often used in jewelry, are thin slices of precious opal glued onto a base material. These are considerably less expensive than solid opals, while still providing the same play of color. An opal doublet becomes a triplet when covered with a thin layer or dome of clear quartz to resist scratches. 

Where Are the Best Opals Found?

Australia is still the leading global supplier of opals with several world-renowned mines including Lightning Ridge, famed for producing prized black opal. Also, the best gem-quality boulder opal in the world is mined only in Queensland.

Opals are also increasingly mined in Ethiopia, producing gems that range in bodycolor from white, yellow, orange and brownish red to “chocolate” brown. And in Mexico, the state of Querétero is known for producing fire opal in yellow, orange and reddish orange to red, some with good play-of-color. 

 

Care and Cleaning 

Opals are delicate but understandably worth the price. They are sensitive to changes in temperature as well as a “crazing” tendency. This means they can easily develop a network of fine cracks or “craze” as they dehydrate. 

Opals are very sensitive to chemicals and changes in temperature. The safest way to clean this October birthstone is with warm water and a mild detergent solution. Other cleaning methods such as ultrasonic or steam might damage the opal or filler material. In the case of a doublet or triplet, prolonged exposure to water may weaken the adhesive.

 

Famous Opals and Opal Jewelry

Now it's time to take you on a magical journey of some of the world's most prized opals!

 

The Virgin Rainbow: Worth more than $1 million, the Australian “Virgin Rainbow" is one of the world's most beautiful opals, a 72.65 carat Black Crystal Opal Belemnite Fossil in a 2.5” elongated “pipe” shape. An amazing feature is that this gorgeous opal glows in the dark! Currently owned by the South Australian Museum in Adelaide. 

The Aurora Australis: Also valued at $1 million, this black opal is named after the Southern Lights due to its display of a harlequin pattern with dominant red, green and blue colors against a black background. It was discovered in 1938 in the dried ancient sea-bed at Lightning Ridge. Weighing in at 180 carats, it is 3” long and almost 2” wide. Its rarity comes from its size and strong, vibrant color play. It even features a distinctive impression of a star fish on one side! It is on permanent display at the Altmann + Cherny showroom in Sydney. 

 

The Black Prince Opal: Another Australian beauty, this “Harlequin Prince” was discovered in 1915 in Lightning Ridge, Australia. This gem weighs 181 carats and exhibits a flag pattern on one side and red flash on the other side. It was stolen in 1991 and its whereabouts are unknown to this day. 

The Butterfly Stone: Another treasure from Lightning Ridge, the “Red Admiral” was discovered during World War and features a predominant red pattern equally visible from all angles. The stone was given the name “Butterfly” because of its resemblance to the British butterfly, the Red Admiral. 

 

The Andamooka Opal: aka 'The Queen’s Opal'. The finest gem crystal Opal ever mined at the Andamooka Opal fields was selected and then cut and polished into 6 stones. Five of these stones were turned into a stunning jewelry suite, presented to Queen Elizabeth II in 1954 on the occasion of her first visit to South Australia. “The Andamooka Opal” as the necklace became known was on display at Buckingham Palace. 

 

Opal Lore

Long considered the gem a symbol of hope, purity, and truth. opal has been regarded throughout history as the luckiest and most magical of all gems because it can show all colors. But in the early 1800’s a novel by Sir Walter Scott cast the opal as mysterious and dangerous, leading to the superstition that it is unlucky for anyone not born in October to wear an opal or buy one for themselves. Luckily, however, as long as the opal is a gift, the wearer’s birth month is irrelevant.  

 

Reminder for When Wearing Opals

Opals can be shattered or damaged beyond repair much more easily than other popular gemstones. They have a hardness of only 5.5, which makes them very susceptible to scratching. Exercise caution especially when wearing an opal in a ring, or reserve that piece for more occasional wear. 

Now it's time for you to find your favorite opal piece, or admire that gorgeous one you already have!

Sources: GIA, GemSociety, Minerals.net, Geology.com

Photos: Altmann+Cherny, Gemme Couture, Australian Open Cutters