There are so many different types of Opal in the world that we wanted to outline exactly where they come from and what makes them all so unique. Opals are one of the gemstones that many people don’t know too much about. We will cover everything from the Black Opal of Lightning Ridge, NSW to the exotic fire Opal of Mexico.
Opal which is found with a natural black or dark background. This background can range from pitch black to grey giving the stone a darkish appearance when seen from the top. It is the dark background which allows the brilliant colours to be accentuated when viewing the stone. Black opal can can show any colour of the rainbow. These are rare and are considered more valuable than others.
The semi-black opal is found on most mining fields. It’s background colour ranges from grey to near black. One of its distinguishing characteristics is an almost smoky appearance. Semi-blacks are from the same family as black opals, but they are not as dark and they carry a slightly less premium.
There is a grading chart for the body tone of Black Opals that is issued by the Opal Association of Australia. It states that a Black Opal must be between N1 and N4, while a semi black Opal can be between N5 and N6
This type has an opaque light background. These types of Opals typically come from the regions of Coober Pedy or White Cliffs. The white body tone means the Opal color is not quiet as strong as in other types of Opals but it is still beautiful.
Crystal Opal has a brilliant crystal appearance, allowing you to look down into the stone. The light background is translucent and creates a very unique look Opal
Jelly Crystal Opal
A solid crystal opal, that is extremely translucent, to the point of being almost transparent.
Boulder Opal is similar to black opal except that the foreground colour is very thin and sits on a brown ironstone base. These types of opal can come with interesting “hills” and “valleys” on the surface. (meaning that the surface is often, but not always, undulating) People who are more “progressive” in their jewellery tastes prefer these stones. Often boulder opal has ironstone inclusions in the foreground and all sorts of odd shapes, which makes them a designer’s delight.
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.
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. Andamooka matrix 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.
Brilliantly colored opals nested in a nugget of ironstone. These types of opals are one of my personal favourites. While they may not have much color their formation is very unique
Because the creation of opal is a natural process it can sometimes be found within substances other than stone.
Opalized shells, crustaceans, 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.
Ethiopian / Welo
Ethiopian or Welo opal is a relatively new form found in Ethiopia. It is volcanic and has a completely different appearance to any of the opal found in Australia.