Solid Natural Opals

Solid Opals are one piece of solid Opal which is cut with a smooth rounded surface (Cabochon cut) rather than a faceted surface. Solid Opals are generally more valuable and expensive than doublet and triplet Opals as they contain a higher carat weight of Opal.
The main varieties of Australian opal available in jewellery shops or specialist opal outlets are light opal, crystal opal, boulder Opal, Andamooka Matrix Opal; dark opal and black opal.

Light Opal

Light Opal has white or light appearance. It has a light or pale background and often displays red, green and blue pinfire. This is the most abundant and affordable type of opal. It usually origin from South Australian fields though some from other areas.

Crystal Opal

Crystal opal is transparent and is pure opal (hydrated silica.) It typically has sharp clarity of diffracted color visible from within and on the surfaces of the opal. When held out of the direct light, crystal opal displays some of the most intense opal color.   And White opal is the most common type of precious opal and is translucent with a creamy appearance which dominates the diffracted colors. All of the opal fields produce white opal with most of it being mined in Coober Pedy.

Boulder Opal

Boulder opal is found sparsely distributed over a wide area of Australian ironstone or boulder country where the opal in fills cracks and crevices in the ironstone boulders. Opal bearing boulder is always cut including the host brown ironstone. Boulder opal is in very high demand and extremely precious. Boulder opal is usually cut to the contours of the opal vein creating a baroque wavy surface and is often freeform and irregular in shape, making boulder opal unique and exclusive among its peers.
Boulder Opal from Queensland is declared by many experts to have the most brightness and best appearance of the Australian Opals.

Andamooka Matrix Opal

Black or darkish bodied opal with bright specs of colour. This is chemically treated Limestone matrix with precious opal in voids. Not common. Andamooka South Australia opal field is the main mining area of Andamooka Matrix Opal.

Dark Opal

Precious opal with a grey or darkish appearance when viewed from the front. Dark opal is relatively abundant.

Usually Lightning Ridge area in NSW or Mintabie in South Australia

Black opal

Rarer than light or dark opal.
Black opal is principally found at Lightning Ridge in New South Wales, Australia. This magnificent gemstone is the most valuable form of opal. It's dark background color, usually black, blue, brown or gray, sets the spectral colors ablaze much like a storm cloud behind a rainbow. Black Opal is a gemstone that has had an important effect overseas, as a product of Australia. It requires a precise meaning so that the quality of this gem can be meaningfully established.
Whether an opal is a black or not can be determined by nearly closing ones eyes and squinting at the face of the stone. All colours are ignored and the overall body tone (blackness level) can then be seen. When this is compared to the scale of blackness given in Figure 1 below it is possible to identify how black the stone is.
Only stones achieving values N1 to N4 on this scale are considered black opals - attracting the additional value associated of this class of opal.

Composite Opal

In addition to solid opal, a number of other varieties composite opal are widely available. Composite stones are generally more affordable than solid stones as beautiful slices, instead of opal stone as a whole, are cut from previous opal stone and being used. In all cases, thin slices of opal are glued to a backing of black backing material to enhance the bright colour of opal slice.

While most composite stones are made from natural opal, occasionally synthetic opal is used in doublets or triplets.

Doublet

Doublets are made by gluing slices of precious opal to a common opal (potch) backing with blackened cement, usually an epoxy resin. The dark backing enhances the colors of the opal. When the backing is brown ironstone it is often called a boulder doublet.

Triplet

Thin slice of precious crystal opal glued between crystal cap on top and black backing. 

Mosiac

Thin chips of precious crystal opal glued onto black backing, can be used in doublets, triplets or on watch faces. 

Inlay

Small thin pieces of precious crystal opal glued directly into channels in jewellery. Inlaid Opals are solid Opals which have been inserted into a piece of jewellery so that the metal surface is level with the surface of the Opal. Inlaid Opal can be any type of Opal, but we usually prefer Black, Crystal or Boulder Opal inlay.