Both opal and tourmaline have been assigned as birthstones for October. I am writing about opal as the more traditional choice of birthstone.
Opal is believed to gets its name from the Sanskrit 'upala' which means precious stone. The Greeks called it 'opallios' and the Romans 'opalus' which we have shortened to opal. It is an ideal ally stone for those born under the sign of Scorpio and like this star sign it is aligned with the element of water.
Opal is hydrated silicon dioxide usually containing 6 - 10% water content; sometimes this can be even higher. Strictly speaking opal shouldn't be called a crystal as it is amorphous and so doesn't have a crystalline structure. Take special care to keep your precious opals from drying out as they may lose their colour play. Don't place them near a heat source or anywhere around dehumidifiers as these can cause them to crack. Never put them in salt to cleanse them. Opals can be porous so do not soak them in water or expose them to oils or chemicals.
The highest quality precious opals are found in Australia and this is their national gemstone. Opals are also found in Mexico, Ethiopia (like the larger opal pictured above) and Peru. Precious opal, especially black opal, is very expensive. In jewellery slivers of opal are often layered up as 'doublets' or 'triplets' to show off the play of colour and make the most of a small piece. The backing layer is usually a black stone such as onyx and in a triplet a clear domed top is added of quartz or glass. If you look carefully from the side you can usually spot the clear layer. Although these are not solid opals they are more affordable and they do contain a thin slice of the genuine stone.
Common opals are more abundant as the name suggests. They are much cheaper and this lovely stone is often found in pastel colours. The properties of opal vary according to the type and colour. Common opals are mostly gentle and soothing stones. Pink opal is an especial favourite for healing emotional wounds.
Opals displaying a play of colours have a higher vibration and stronger action. Precious opals may be used for developing psychic perception and to support a shift of consciousness. The white opals have a high angelic vibration, black opals are more magical in their nature and can take you on a journey inwards. Fire opals come in shades of orange and red and can stimulate your creative energies.
There is a lingering superstition around opals being unlucky, however historically across many cultures they have been regarded as lucky stones. In Aboriginal mythology Creator came down to Earth on a rainbow. Where his foot touched the ground the rocks were transformed into opals shining with all the colours of the rainbow. The Roman Pliny the Elder wrote that opal is, "Made up of the glories of the most precious gems, to describe them is a matter of inexpressible difficulty. For there is amongst them the gentler fire of the ruby, there is the rich purple of the amethyst, there is the sea-green of the emerald, and all shining together in an indescribable union. Others, by an excessive heightening of their hues equal all the colours of the painter, others the flame of burning brimstone, or of a fire quickened by oil."
One of the sources of the 'bad luck' belief is relatively modern and comes from a work of popular fiction. In 1829 Sir Walter Scott wrote a novel, Anne of Geierstein, in which the character Lady Hermione wears an enchanted opal which responds to her moods giving off angry red flashes when she is annoyed and sparkling brightly when she is happy. Her opal loses its colour after a drop of holy water is splashed upon it. She faints and is taken to her bed. Later all that is found of her is a small pile of ashes. This fictional story led to the public's distrust of the stone and it rapidly fell in popularity. It may be that the real tendency for opals which are kept in the wrong conditions to crack and lose their colours contributed to this idea of bad luck.
Opals have recovered their rightful place as beautiful and desirable gemstones in modern times. Queen Victoria helped to restore their popularity by wearing opals herself and gifting opals to her daughters.
My own belief is that precious opal is neither 'lucky' or 'unlucky', but that the darker opals do have the ability to bring out both your inner light and shade. Black opal may reveal characteristics that lie deep within one's own character, fire opals may bring up repressed issues you hold around sexuality, thus opals are perfect for Scorpios who especially need to understand and embrace their whole Selves including those aspects influenced by their ruling planets of Pluto and Mars. Yes you may get glimpses of your shadow side when using opal and you may become more aware of your emotions, moods and drives, but this is all part of your development as a whole person and your Shadow may bear you gifts which you have yet to recognise and integrate.