How can you tell one opal from another? What is the difference between various opals? And why is it important to do so?
Opals are unique in that they are not gems and unlike diamonds or rubies. They are made of an entirely different material but, like many precious stones, have their differences, and these can equate to thousands of dollars so it is wise to have some understanding of opals and the differences between them.
Some of the more common opals available are:
Matrix OpalThe Black Opal has a dark body tone which causes a brightness of color unmatched by the other opal types. Black Opals are only mined at Lightning Ridge in New South Wales in Australia and considered very rare and are the most expensive of all opals
White Opals, by contrast are almost cream and sometimes called a Milky Opal Being white they do not show the internal color so well as the black and are generally purchased as white opals only. In an excellent quality stone however there can still be seen some color flashing. These can be purchased relatively cheaply although a really good quality one can set you back a few hundred or thousand dollars.
Boulder Opals are different again. These have a solid layer of brown ironstone on the back of the stone. They originate from large ironstone bounders, hence the name, underground.
A Crystal opal can be the same as above but has a transparent or semi-transparent body tone which means you can see through the stone. Crystal opal can have a dark or light body tone hence, “black crystal opal” and “white crystal opal”
A Fire Opal is an American term and describes any opal which has a significant amount of red coloring. Red is the rarest Color in opals, so these are quite valuable. Often confused with a ‘Mexican fire opal’ which is different yet again and displays orange instead of red coloring.
A Matrix opal is where the opal occurs as a network of veins or infilling of voids or between grains of the host rock. A Matrix comprises precious opaline silica as an infilling of pore spaces in silty claystone or ironstone. the matrix opal shows a fine pinfire color in the natural state. very rare also.
It is important to understand and know what you are purchasing and further information is available at the links on the right.