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Black + Dark Opal, Natural Opal Type 1, Body Tone N1 to N6

The definition of dark opal is any opal with a body colour dark enough to enhance the contained or overlying spectral colours. Any shades from black to light grey, very dark brown to light brown or dark to light amber would classify as dark opal irrespective of the origin of the opal. Most boulder opal is classified as dark opal.

Dark Opal is commonly called Black or Semi Black Opal. Most black opal originates from Lightning Ridge while semi black with a background colour from dark to pale grey can originate from Lightning Ridge, Mintabie (S.A.) and Coober Pedy (S.A.). Opal with a translucent or transparent dark brown to amber body is classified as dark opal or commonly 'black crystal' opal.


Black opal from Lightning Ridge is the pinnacle in terms of price, of all the opal. The finest examples can exceed AUD $20,000 per carat retail. However, stones of this grade are rare, hence the price.

Commercial quality forms over 98% of production where prices range from an affordable retail of $20 per carat upwards, averaging around AUD $500 per carat retail.

Black Opal forms less than 15% of the total production from Lightning Ridge. Dark opal, from dark grey to pale grey base colour form around 60%. While the balance is Light Opal (crystal and translucent) and 1 or 2% Black Crystal.

Black Opal itself has a body colour of jet black to very dark grey, these and only these body colours can be classified, Black Opal. Dark to light body colour is classified as Dark Opal.

As can be seen from the production percentages, Black Opal is a rare gem, total production annually may be similar in carats to the famous pink diamonds from Western Australia. The most expensive commercial gem in the world, where prices can exceed retail over 1 million dollars per carat.

Although its not envisaged Black Opal could reach this price, current price levels make it a bargain, particularly considering the declining levels of production. Most new discoveries of Opal in the outlying satellite fields of Lightning Ridge are dark opal not Black Opal. The bulk of Black Opal comes from Lightning Ridge itself plus areas to the west and NorthWest within a radius of 20 km from Lightning Ridge. This area is the most intensely prospected, the production comes from isolated pockets missed by miners and the working of old mines originally classed as worked out. There has been no discovery of a new field producing true black opal for many years. I repeat, at current price levels, true Black opal is a bargain, even at prices 3 or 4 times the current level it would still be a bargain.

Light Opal, Natural Opal Type 1, Body Tone N7 to N9

The definition of Light Opal is any opal having a pale colour background which does not enhance the contained or overlying spectral colours. The background can be a pale shade of grey, brown, yellow, amber or even green, plus white.

Most Light Opal originates from the South Australian fields but is also produced at Lightning Ridge where light crystal opal is abundant.

Boulder Opal, Natural Opal Type 2 and 3, Body Tone N1 to N9

The definition of Boulder Opal is any opal having a sedimentary ironstone back with a naturally adhering face of opal silica which can range in colour from crystal clear to cloudy or milky and into a light yellow background containing the spectral colours. Boulder Opal can be dark opal or light opal and when the face is light or white is valued as a light opal but when dark, normal boulder values apply.

Boulder Opal is traditionally cut baroque or free-shape with a baroque face. Baroque boulder opal is traditionally priced per piece. There is no assessable way to do this. Most are priced by eye relative to known sales.

Boulder Opal can however be priced by the carat and the written methods can completely support the valuation at any level of selling. Boulder is currently the opal with the most sales appeal and in particular should have a written basis of valuation along with all other opal. One hopes that this program may assist in achieving this. Boulder Opal with a light opal face is valued under the normal Light Opal category.