Black opal

Opal which is found with a natural black or dark background. This background can range from pitch black to grey giving the stone are darkish appearance and when seen from the top is opaque [Not allowing light to pass through]. It is the dark background which allows the brilliant colors. Black opal can be any color. The specimen pictured has a dominant color of blue. It is approximately 1-1/2 cm in length.[This particular stone has now sold]

Dark Opal

Dark opal is found on most fields. It's background color ranges from grey to near black.. Black opals are in the same family as Dark opals [also opaque- not allowing light to pass through]. They are just dark opals with a blacker background. As the background of this stone becomes lighter and greyer it gets closer to light opal and its sometimes difficult to decide whether a dark opal should be categorized as dark or light. Its often in the eye of the beholder.

White opal

A solid opal with an opaque [non see-through] light background. White opal is often called milk opal because of its light appearance. Crystal opal is of the same family but it is more translucent and sometimes transparent whereas the color of white opal is on the surface. This type of opal can appear in all fields but Coober Pedy is famous for it.

Crystal opal

An opal with a brilliant crystal appearance. Depending on the density of the color, the stone can be either opaque [Not allowing light to pass through] The opposite of transparent [Easily seen through] (glass like) or translucent [Letting light through without being transparent], but most good quality crystals are translucent, allowing you to look deep into the stone without seeing right through it. [transparent]

Jelly Crystal opal

A solid crystal opal that is extremely translucent, to the point of being almost transparent. The sample specimen is from the Coober Pedy mines. It had to be photographed against a dark background to bring out its color.

Boulder opal

Similar to black opal except that the foreground color is very thin and sits on a brown ironstone base. These stones at times can come with interesting "hills" and "valleys" on the surface.(meaning that the surface is often, but not always, undulating) These stones are preferred by people who are more "progressive" in their jewelry tastes. Often boulder opal has ironstone inclusions in the foreground and all sorts of odd shapes which makes them a designers delight. However, many boulder opals have no inclusions and look much the same as dark or black opals. In fact, boulder opal [usually opaque] which has a dark appearance is also categorized as black or dark opal.

Boulder opal matrix

Matrix actually comes from the word "mother" or "womb", meaning that the ironstone is the "mother" that holds the "baby" which are tiny flecks of precious opal. A characteristic of boulder matrix opals is that the colour is usually peppered throughout the stone.

Andamooka Matrix

A more porous opal found in the mining field of Andamooka. When it comes out of the ground it is quite pale but by treating it with a carbon dye process it eventually looks like real black opal. An Andamooka matrix opal can be an affordable alternative to a genuine black opal--but buyers beware--an honest opal dealer will tell you whether you are buying an Andamooka matrix or a genuine black; a disreputable dealer may not.

Yowah Nut

Brilliantly colored opals nested in a nugget of ironstone. The specimen is a partial Yowah Nut with a crystal opal kernel and bands of opal matrix surrounding it..These stones have endless varieties of patterns and colors, making them a designers collectors dream. (For a full history of this small unique Yowah opal mine, order Len Cram's book Beautiful Yowah.)

Picture Opals

Uniquely patterned boulder opals where an object is clearly visible. The specimen has been named "the shrimp." or as Australians would say "the Prawn' Picture opals are both rare and unique, making them much sought after by opal collectors. This is one of the most outstanding examples in Peters private collection.

(The whole private collection is for sale for one million dollars 'Beautiful Yowah' by Len Cram. page 7 Order this book and our CD 'Opals for the Ordinary Bloke' in the books and CD section of the site.)

Opalized Wood

Because the creation of opal is a natural process, opals can sometimes be found within substances other than stone. The specimen shows opalized wood. Some, but not all, of the wood fibres have opalized. (Photo is from Len Cram's book 'Beautiful opal' page 44..)

Opal fossils

Opalized shells, crustations, sea creatures, snails, animal claws and bones, are some of the many objects that over time can opalize when buried in the unique environment of Australian clay and left undisturbed. These chunks of opal are marvelous conversation pieces for your mantlepiece or office desk and come with full explanation. Pictured is a cluster of opalized shells. These indicate evidence of an ancient flood.

Specimen

A chunk of opal that is either left in its natural state or given a polish or varnish to show off one aspect or feature of the stone. Opal specimens are sought after by rock collectors, who generally display them on a desk or shelf.. The example is actually half of a specimen pair. With a specimen pair, both halves actually fit together, but are usually displayed side by side to show off the opal in the centre.

Mosaic Opal

The previously described opals are all naturally formed. The mosaic opal is a man-made creation. Slivers of genuine opal are assembled into an irregular tiled pattern with rivers of black potch framing each unique opal tile. Mosaic opals make stunning stones for all types of jewelry and allow the jeweler to include a wide range of colours within an affordable piece. Now, there is a natural stone that looks very similar to mosaic opal. The natural phenomenon is called the harlequin opal. It is the rarest and most expensive opal.