Opal

Opal is an October birthstone. It is sometimes replaced by tourmaline, in a mother's ring for example.

Opal is known for its display of flashing rainbow colors called play-of-color. There are two classes of opal: precious and common. Precious opal displays play-of-color, common opal does not. There are five main types of opal: white or light opal, black opal, fire opal, boulder opal and crystal or water opal.  Opal contains up to 20% water trapped in its silica structure, and for this reason it can crack in extreme temperature changes and is more fragile than other stones of equal hardness.  Opals will vary widely in appearance and quality. There are three main aspects of an opal’s quality: color, pattern and clarity.

Common types of assembled opal are the doublet and triplet. The doublet is a thin layer of opal cemented to a backing. The backing is often composed of a dark stone, black onyx, for example. The triplet is a thin layer of opal between a domed top of colorless quartz and a dark backing.  They sell for only a fraction of the price of boulder opals, but they allow one to make finished gems from thin opals. 

Australia’s mines began to produce opals commercially in the 1890s and it quickly became the world’s primary source. One of the most famous opals, The Pride of Australia / Red Emperor, was found in 1915, by 1954, it had toured at least five World Fairs as "the greatest opal of Australia".

Opal is probably the most controversial gemstone in regards to myths. There are several legends about all sorts of gemstones, but opal most frequently comes up with superstitions, such as:

• Only people born in October are safe to wear them
• Opals should neither be given or accepted as a gift
• Engagement rings must not contain an opal or the bride will quickly become a widow
• White or milky opals are jinxed, but black opals are extremely lucky
• Setting opals with diamonds negates the stone's ability to draw sorrow to the wearer as diamonds are said to have power over the opals.
• Opals turn pale when poison is close and they lose their shine once the owner dies

So why did opal's bad luck story originate?

The most popular source of the story that opal is bad luck began with the 19th century author, Sir Walter Scott and his novel called Anne of Geierstein in which the character, Baroness of Arnheim, wears an opal talisman with supernatural powers. According to the story, the Baroness dies when a drop of holy water falls onto the opal and drains the stone of its color. His book was very popular and people began to associate opals with bad luck and death. Sales of the gemstone dropped and remained low for years after. 

Diamond traders also played a big hand in the bad luck myth through one of the oldest marketing tactics around – word of mouth. A large amount of opal was making its way to trade markets, causing DeBeers to panic at the prospect of opal becoming more popular than diamonds and so, to ensure diamonds retained a bigger market share, DeBeers promoted a rumor that opals were bad luck. Another possible reason opals were promoted as bad luck by diamond traders is that the gemstone is softer than a diamond - around 6 versus 10 on Mohs hardness scale, making them tricky for jewelers to work with.