Opals are beautiful gems, with the finest Family Opal specimens containing every colour of the rainbow. The name means ‘precious stone’, and is thought to have come from the Latin “Opalus” and the Greek “Opallios”.
Their unique internal colours are one of the most fascinating visual effects created by nature and is Optical Properties Displays opalescence correctly referred to as “play of colour”. Opals are doubly attractive as they often also have a beautiful iridescence (known as ‘opalescence’).
Opals were created from hydrated silicon dioxide, and were formed when water-based solutions containing silica, deposited a gel- like substance in gaps and crevices in rocks. Because of this they often form around areas where there are hot springs or geysers. This process is fairly common and often the resulting stone is a lacklustre ‘common Opal’ which is ‘amorphous’, meaning that the atoms are arranged randomly within the stone and there is no crystal structure. Common Opals also come in a variety of different base colours, however these often have little or no play of colour and are therefore considered to have very little value.
Gem-quality Opals do, however, have a crystal structure. They are loved for their kaleidoscope of colours and internal flashes of almost neon coloured lights. There are several varieties of gem-quality Opals and the names used for them by the gemstone industry can be quite confusing to many people. When you hear White Opal, Grey Opal or Black Opal, the name is referring to the background colour of the Opal. See it as a canvas for a painting on which beautiful colours are to be thrown in a random inspiration of modern art.
Boulder Opal consists of fine layers of natural Opal which have formed naturally on ironstone rock. Much like Ammolite, it is removed from its host rock while it is being cut, and then placed back onto it. This means that for most Boulder Opal the finished gem is actually a doublet or triplet opal. Boulder Opal from Queensland is declared by many experts to have the most brightness and best appearance of the Australian Opals
Opals have been considered both good luck and bad luck throughout history. They were as precious as Diamonds to the ancient Greeks and used in jewellery by the Romans, whereas in Russia the stone was considered by the Tsars to symbolise the evil eye. When Europeans first went to the New World they found the Aztecs of South America mining the gem, and due to its rareness and beauty they took many back to Europe to be presented to the royal courts.
Even Opals set in jewellery still contain an element of water and this can vary between 3% and 20%. Because of this, Opals are considered to be a fairly soft precious stone, measuring between 5.5 and 6.5 of the Mohs scale.
Common Opals can be found all over the world, whereas gem-quality Opals are mostly mined in Australia; in fact, some reports claim that 97% of the world’s gem-quality Opals are sourced from here. Other areas are Mexico, South Africa, Brazil, Honduras, United States, Czech Republic, Guatemala and Romania.
Not all Opals are opaque and there are other body colours available too. Take a look at Fire Opal which, due to its incredible popularity, we have given its own section in this book.
Recently I managed to find a small parcel of Yellow Opal from Tanzania. These gems are totally stunning. Whilst they don’t have the transparency of the finest Fire Opals, they do have a body colour which is a beautiful pastel yellow. I have so far only discovered a small amount of this gemstone (less than 100ct), but I have just dispatched one of my buyers to Tanzania to try and find more. Keep a look out on both the The Genuine Gemstone Company website and GemCollector.com for more information.
One of the best discoveries recently has been Pink Opals from Peru. Gem hunters the world over are always looking for naturally coloured pink gemstones, as it is one of the most desirable of colours and provides a real feminine touch to jewellery. The Pink Opal which I have recently sourced from South America is stunning. We have had the pieces cabochon cut in our Jaipur cutting house and not only is the colour incredibly attractive, it has a wonderful surface lustre too.
In May of 2009, I secured a parcel of gemstones from a trader who lives in Mali in North Africa. He normally supplies us with Garnet, but had unearthed an opaque green gem and wondered if we were interested. At first we thought it might be Jade, but as this was so uncharacteristic for the region we sent the samples off to the laboratory to have it checked out. When the results came back, we were amazed that it turned out to be a green Opal! Therefore we decided to call it Mali Opal after its origin. So far we have only secured a small amount of the gem and have had it faceted into both Ovals and Cabochons. Keep your eyes on GemCollector. com and The Genuine Gemstone Company to see if we are able to find more!
