Opal is regarded as one of the most beautiful and magical gems. The three most well known types of opal are White Opal, Black Opal, and Fire Opal. Opals display all colours in them but with a different background colour. White Opals have a white or light grey background colour, Black Opals have blue, grey, black background colour. Fire Opal is the exception as it doesn't always show a display of colour.
Many cultures believe Opals to hold special powers and have psychic abilities. While it is also thought to symbolize truth and hope.
Current market information from Paul Brereton, gemologist: Australian opals generally have the best play-of-colour. There are some opals being sourced from Ethopia that have a strong play-of-colour but the background colour has a brown overtone and the colour platlets are larger then Australian material. They also have a "watery" appearance. The traditional source in Australia for white opal is an area called Coober Pedy.
Most of the worlds fine black opals are mined in an area called Lighting Ridge in Australia. Black opals command a large premium over white opals. The three factors that determine the price of a black opal are:
1. Background colour: A background colour of black commands the highest price, while a pale grey is less valuable.
2. Play-of-Colour: A play-of-colour that is throughout the stone is more valuable while where there are spots that lack any play-of-colour will have a negative on value.
3. The colour red is in the play-of-colour: While green and blue are common colours in black opals once red is in the play-of-colour the stone will command a large premium. A black opal with only green and blue is referred to as a "Peacock" black opal.
Sources- Australia, Brazil, Mexico. Hardness- 5-6.5 on Mohs scale. Toughness - Very poor to fairOpal is the birthstone for October. To view our collection of Opal jewellery please contact us at webenquiries@brereton.ie. 
