The colours and patterns seen in opal are known as Opalescence. – FALSE
‘Play of colour’ is the correct term for the iridescent effect and rainbow colours seen in Opal. Opalescence is correctly applied to the milky effect seen in common opal or potch, moonstone or opal-glass. It is due to the scattering of light by small particles within the stone.
Black Opals are found at Lightning Ridge in New South Wales. – TRUE
Black Opal is an exceptionally rare and finite Gemstone. The world’s finest Black Opals are found at Lightning Ridge; very few significant finds have been made elsewhere. Contrary to popular misconception even the vast majority of Opals found at Lightning Ridge are actually white or grey in body tone and cannot be classified as Black Opal.
Opals should be oiled on a regular basis to keep them from cracking. - FALSE
Although commonly used and prescribed neither glycerine nor mineral oil are recommended for storage or even short term use on Opal. Glycerine is hygroscopic, it can theoretically draw water out of Opal which may actually cause it to craze. Clear mineral oil will prevent water from moving in or out of the stone, by infiltrating the pores in Opal it will slowly decompose discolouring the stone and ultimately it can never safely and completely be removed from the stone.
Queensland Boulder Opals are the most durable variety of solid Opals. – TRUE
By virtue of its iron content Queensland Boulder Opal has a higher density and hardness than all other varieties of Opal. Boulder Opal is a natural fusion of Ironstone and Opal, this twin composition assists in the absorption of heat and pressure. The natural water content in Boulder is the lowest of all the Opal varieties and its maintenance is facilitated by transferral between the two constituent materials. Therefore most experts regard Boulder Opal as the most stable variety of Opal.
Boulder Opals are Natural Doublets - FALSE
Doublets are cheap man made products; they are often made with ironstone backings to resemble Boulder opal. A Natural Doublet is a fallacious concept and a misnomer for Boulder Opal which a naturally occurring variety of solid Opal.
Opal artefacts found in a Kenyan cave by archaeologist Louis Leakey date back to 4000 BC. - FALSE
Dr.Leakey found some gemstone beads, none of which were in fact opal, at a site which was eventually radiocarbon dated to 960BC.
A single Opal of any variety may display more colours than any other gemstone. - TRUE
Opals of any body tone, that is black, white or boulder based stones may display any one, or more, or even all of the spectral colours (referred to as multicoloured). Most other gemstones are monochrome or at best pleochroic, meaning they display various hues of a primary colour. Rare examples of other gemstones exist which are bicoloured or multicoloured however the colours and definition between colours do not change as they do with Opal. Play of colour is unique to Opal, the possible combinations of changing patterns and colours are infinite, the palette also goes way beyond the primary colours.
Opals should not be immersed in water whilst doing the dishes or washing ones hands. - FALSE
If you can comfortably put your hands in the water then Natural Opals will not be affected by such immersion, warm soapy water is actually an excellent cleaning agent for your Opal ring. However Doublets and Triplets which are man made composites (thin slices of opal adhered to other backing materials) may lift or become unstuck by repeated or prolonged bathing.
Opals are Precious not Semi-Precious Gemstones. – TRUE
As the ‘Queen of Gems’ Opal takes pride of place amongst her precious gemstone peers – Diamond, Sapphire, Ruby and Emerald. When an Opal displays ‘play of colour’ it is defined as precious. However most of the Opal that is found is known as potch or common opal. Potch is not precious as it does not display multiple colours that change with the angle of observation.
Opals are fragile and therefore cannot be classified as Precious Gemstones. – FALSE
Opals are similar to Emeralds in toughness, both are sensitive to pressure and care must be taken in heating them and setting them into jewellery. Boulder Opal has the same density as the Beryl gemstone family of which Emerald is a species. Black Opals rival Diamonds in their price per carat, yet the finest Opals are truly unique whereas fewer diamonds can claim that distinction.