The word Opal originated from the Greek word ‘Opallios’ meaning to see a change of colour, or the Latin word ‘Opalus’ which means precious stone. It is one of our favourite gems and we use it in nearly all of our ranges of jewellery.
Opals were formed 30 million years ago, mainly in an area that we now know as Australia. It is believed that an inland sea covered central Australia, and huge amounts of silica sediment were deposited around its shoreline. This watery silica sunk into the earths surface, filling crevasses in the rocks and settling in layers of clay. Once the water had evaporated it left behind the silica which hardened into precious opals.
Australia produces around 95%of the worlds opals but they can also be found in America, Mexico, Ethiopia and a few other countries.
The majority of opals found are white, this is known as ‘common opal’. It has a milky or pearly lustre known as ‘opalescence’. Rare specimens of opal, which are only found in a limited number of locations worldwide, have brilliant flashes of colour when turned to the light and are known as ‘precious opals’. The term ‘play of colour’ is used to describe the shifting colour flashes in the high quality stone. ‘ Common opals’ do not exhibit a ‘play of colour’.
Opals can be found in other colours as well as the more common white and blue. Perhaps one of the best known are fire opals. These are transparent to translucent opals that have a bright fire-like background colour of yellow, orange or red. Often exhibiting no “play-of-color”.
In our work we use different opals, not only in colour but also in their structure.
Solid opals. These opals have been cut into shape from a solid single piece of rough. As we have mentioned in a previous blog these opals are delicate and are very difficult to set.
Opal doublets. Some opal in the rough is found in very thin layers but has brilliant fire or play of colour. These pieces, as well as slithers that are cut from larger solid opals, are made into opal doublets. Opal doublets consist of two layers, a slice of opal and a backing. The backing can be made from a number of things, black potch (colorless opal), black glass, hard plastic, and other materials. It is usually a black colour as this helps to promote the play of colour and luminosity of the opal that is on top. The major advantage of the doublet is the strength that it gains because of the backing, they are easier to work with than the solid opals.
Opal triplets. These stones are similar to the doublets but have a clear top section glued on. This is made from clear quartz, spinel or other clear material. This makes the opal more robust and protects it from abrasion and impact. It also acts as a magnifying lens to enhance the colours of the opal layer.
Lab grown opals In our Asymmetric, Matching and Imprint ranges of jewellery we also use Lab grown opals. The lab made opal is chemically, physically and optically identical to the gems that occur in nature. The main difference with natural opal and lab grown, is that the occurring process has been sped up in the laboratory. Also, because natural opal contains water from ancient seas, it can be subject to cracking or “crazing,” especially when exposed to extreme heat and dryness. In lab grown opals the water has been replaced with silica, making them much more stable.
We use this stone for many reasons. Because of the nature of opals, the colour and pattern differ immensely. With the lab grown opals we can get similar colours more consistently, with greater clarity and fewer flaws. The durability and resistance to cracking and abrasion are also a big factor. Lab grown opals also have less of an impact on the environment than mined gems and have a lighter carbon footprint. Another important reason is the cost. Natural gemstones are becoming more difficult to obtain and therefore are getting more expensive. You can find all of the above jewellery featured in this blog on our website.
Some world famous opals.
The genuinely awe inspiring Galaxy Opal.