October is represented by two colourful birthstones, Opal and Tourmaline.
Opals are found in many countries, including the USA, Brazil, Mexico and southern Africa but the vast majority of Precious Opal comes from Australia. Unlike most gemstones that have a crystalline structure, a mineralogist would describe Opal as being amorphous (a non-crystalline solid) built from layers of microscopic silica spheres, and it is this property that allows for “the amazing play of colour” for which Opals are renowned. These brilliant flashes of colour make each Opal unique and the colour combination brings to mind the colours of fall, another reason the Opal is the perfect representative for October.
If you are unfamiliar with Opals, you might be surprised to learn that there are several varieties of Opals. Perhaps the most valuable is the Black Opal which is exclusively found in the Lightning Ridge area of New South Wales in Australia. The Black Opal boasts a dark matrix against which the spectral “play of colours” is vividly contrasted. More common are Opals characterized by a white body tone. Usually, you will find that both Black and White Opals are shaped and polished into a cabochon cut, a smooth convex top and flat bottom without any faceting. Another Opal worthy of note is the Mexican Fire Opal. Whereas Australian Opals are formed from the deposits of silica dissolved in groundwater, the Fire Opal is volcanic in nature and also differs from their southern hemisphere relatives as they are transparent, red in colour and often presented with a faceted cut.
It is said that in ancient times, the Bedouins believed that Opals held lightening as evidenced by the “play of colour”, and fell from the sky during thunderstorms. The lore surrounding Opals suggested that they provided the gift of prophesy and protection from disease.
Also, Opals were thought to symbolize purity and hope.
The Opal is sometimes called the “rainbow gem” because all the colours of the rainbow will be found in the pattern of colours in a fine quality stone. Coincidently, the alternative birthstone for October, Tourmaline, is also referred to as a rainbow gem. The reason the Tourmaline has earned this moniker is due to the number of varieties of Tourmaline that exist.
From the more common red (Rubellite), and the spectacular and extremely expensive neon blue (Paraiba) Tourmaline to the tri-colour “Watermelon Tourmaline” and the many other varieties and colours available, Tourmaline is truly deserving of the rainbow gem moniker. Tourmaline is mined in over a dozen countries and often some varieties of Tourmaline would be mistaken for more valuable gemstones. For example, the Chrome Green variety could be mistaken for Emerald and the red variety (Rubellite) might be mistaken for Ruby as was the case in 1777 when King Gustav III of Sweden presented Catherine the Great with “Caesar’s Ruby”, a pendant containing what was thought to be a 52 carat ruby and reputed to have belonged to Julius Caesar. It was later determined to actually be Rubellite, not Ruby as everyone believed!