Opal - October birthstone
Mohs Hardness 5 to 6.5
Mined From Australia, Brazil, Mexico, USA, Peru, Ethiopia.
Typical Cutting Style Cabochon and Freeform
Colour White/Light Opal: Translucent to semi translucent, with play-of-colour against a white or light grey background, called body colour. Black Opal : Translucent to opaque, with play-of-colour against a black or other dark background. Fire Opal : Transparent to translucent, with brown, yellow orange or red body colour. This material which often does not show play-of-colour is also known as Mexican opal. Boulder Opal : Translucent to opaque, with play-of-colour against a dark background. Fragments of the surrounding rock, called matrix, become part of the finished gem. Crystal/Water Opal : Transparent to semi-transparent, with a clear background, this variety shows exceptional play-of-colour.
Play-of-colour occurs because Opal is made up of sub-microscopic spheres stacked in a grid like pattern like layers of ping pong balls in a box, this structure breaks up light into spectral colours.
Chemistry SiO2 nH2O hydrous silicon dioxide.
Treatment Impregnation with oil, wax or plastic (this improves or creates the play-of-colour and prevents or disguises fracturing. Black plastic also creates the appearance of black opal.) Soaking in dye, silver nitrate or sugar and acid treatments. Smoke impregnation is another treatment used for Opal.
Inclusions There might be areas of an Opal that lacks play-of-colour or that contains mineral inclusions or patches of rock matrix. In some natural Opals dehydration can cause a network of cracks known as crazing.
Cleaning & Care Warm soapy water and a soft toothbrush will help maintain the lustre of your Opal.
DO NOT use harsh solutions or abrasives, using ultra sonic machines and steam cleaning is not recommended. Sudden temperature changes and prolonged exposure to daylight can easily dehydrate your Opal. Opals are sensitive to acids and alkalis and due to its porous nature avoid perfumes, lotions and soaps on your Opal jewellery and we recommend removing your opals when washing up. Visit us on a yearly basis for a FREE clean and polish service.
Storing Your Opal When you are not wearing your Opal jewellery place it in a moist piece of cotton wool in your jewellery box as it is easily dehydrated and this help lock in some of the moisture within the stone. Store your Opals in a separate compartment in your jewellery box to avoid damage from harder gemstones as this can cause cracks & scratched to your Opal jewellery.
Interesting Facts Many cultures have credited Opal with supernatural origins and powers, Arabic legends say that it falls from the heavens in flashes of lightening. The ancient Greeks believed Opals gave their owners the gift of prophecy and guarded them from disease. Europeans have long considered the gem to be a symbol of hope, purity and truth. It is also regarded as the most magical and luckiest gem due to its play-of-colour and was once thought to prolong and preserve the life and colour of blonde hair.
Opal contains up to 20% of water that is trapped within its silica structure