Opal is the birthstone for October, and Australia’s national gemstone.
It is a hydrated amorphous form of silica, classed as a mineraloid. Opal is formed from a mixture of silicon dioxide and water. This creates silica deposits that eventually form an opal. It comes in multiple colours. This includes white, grey, red, orange, yellow, green, blue, pink, brown and black.
Precious opal is rare and changes colour from different angles. Common opal is beautiful but just comes in one colour. Fire opal are fire hued and come in precious and common varieties.
Texture wise, there are solid opals, boulder opals (gems with seams of rock) and matrix opals, which are a close mixture of rock and gem, very suitable for cabochons.
Opals can be faceted but it has to be done carefully, due to the fragility of the mineral.
Are Opals Bad Luck?
Black opals were thought to be focal stones for evil witches and sorcerers. Milky opals were associated with the evil eye. There was an odd belief that the gem could cause people to become invisible and teleport. This lead to them becoming the patron stone of thieves and assassins.
They also became associated with random maladies, such as the Plague, or in Spain, Cholera. A spate of deaths were attributed to an opal ring, rather than the virulent disease devastating the country. This was influenced by the fact that some opals can change colour when exposed to water or heat.
So for example, when the body heat of a person faded upon death, the colour of the opal would appear to fade too.
The gem is softer than other stones like diamond and sapphire, and thus easier to break. This has also contributed to the reputation of opal as being unlucky.
Opal Facts
- Australia produces about 95% of the world’s opals.
- This fact is referenced in Terry Pratchett novel The Last Continent, which opens with opal miner Strewth unearthing one of the main characters from a crystalline casing.
- Opal has been found on Mars!
- Queen Victoria helped revive opals by keeping a personal collection and gifting them to others.
- The Romans used opals as good luck charms.