We already covered opal gemstones in a libra birthstone post, but this week we want to focus in on the more technical aspects of this unique stone: the different types, colours, and where in the world they can be found. Opal gemstones, the libra birthstone as well are made when rain soaks into very dry, desert-like ground, like you find in the outback of Australia. This water soaks down deep into the rock below, taking with it something called silica, a dissolved mix of silicon and oxygen (from the air). When the rains stop, and the water in the ground has evaporated in the heat, deposits of this silica are left in between layers of rock – forming opals, with their rainbow of colours. Opal can be categorised into many different categories, but the main groups of opals you are likely to come across are called the following:
Examples Of Opal Gemstones
White opal: this type of opal is translucent to semi-translucent (meaning light passes through it, highlighting its colours) and often flashes of colour can be seen against a background of white or light grey.
Boulder opal: boulder opal gemstones feature its colours against a light to dark background, but parts of its surrounding rock have become part of the finished gem – hence the name. This particular gem is our favourite to use in one of a kind jewellery, because normally, the colours are so vivid, vibrant and truly eye-catching. Matrix opals are unique boulder opals, found in a ‘host rock’, through which deposits of opal run through like veins.
Crystal opal: Crystal opal gemstones are completely transparent to semi-transparent (meaning you can see through it), with a clear background. Because of its transparency, this stone can feature extraordinary flashes of colour. The best opals in the world are found at mines in Lightning Ridge, Australia, and have been being bought from there since the 1800s. Ethiopia is also a source of some very beautiful opals, the libra birthstone, but because of their formation they can change to become milky over time, so buyers should be aware of this when purchasing an Ethiopian opal.
Another thing that buyers should look out for when choosing their opal gemstone, or piece of opal jewellery, is whether the opal they are looking at is solid stone, or something called a doublet or triplet opal. Doublets and triplets are slices of opal, attached to a black backing and then, in the case of a triplet, affixed with a clear dome, these are manmade. These are far cheaper than solid opals as they contain less stone, and can still be striking – however, here at Origin 31, we don’t use these as we feel that gemstones should be kept as nature intended. You can normally tell if your opal is a doublet or triplet by looking at its side; if the stone has been attached to a backing with glue then the join will be completely flat and straight. This can be tricky when the stone is already set in jewellery.
Opal gemstones for us are one of our favourite stones as no two opals are the same. The colours that the stones illuminate are breathtaking, a dreamscape or even a galaxy; when we design we truly let the opal do the talking which is why each jewellery design using an opal is practically bespoke. Opal also represents the libra birthstone another reason to use this beautiful gem as inspiration for bespoke jewellery, every piece is one of a kind jewellery.