What IS black opal? Well, for a start, it’s NOT BLACK and that’s why it can be confusing to the novice wanting to buy one. The term Black Opal was first coined to fill a need to define its difference from previously known opals which were always of a pale or clear color. Blacks are gems with a dark background.
What is the color of black opal? The answer is ANY color. Blacks can be blue, green, yellow, red, orange, purple and of course, a combination of all these colors. Remember, a good quality black opal is not black. It has the ability if you could call it that, to suck all the colors from the rainbow and display them in all their variations.
How do you know a good quality black opal? The main thing is to allow your eye to perceive what is brighter and more dramatic. The blacker the background, and the brighter and more stunning the foreground is the best indicator of a good black opal.
What is the difference between a black opal and a dark one? Well, they are really from the same family. All black stones are dark opals but one with a background that is grayer is called a dark opal, not black. For the purpose of identification, often dark opals will be listed as black opals because not many people know the technicality, but the fact is that a good quality black opal is always very dark in the background.
How come some black opals with grey potch (even light grey potch) are still called black opals? This is a very good question, and the answer is that sometimes there is a strip of really black potch directly under the foreground color, giving the stone a really dark background. But then under that strip of black potch, there is a strip of lighter colored potch, even grey to white. This doesn’t matter because the important part is that the background of the color is still black.
Why do black opals from Australia have such a good reputation? Because Australia, being a very old dry continent, has gemstones that have dried out over a very long period of time and are less prone to cracking or crazing. There are some very beautiful stones from Africa and the USA and South America, to name a few of the countries but generally they are only appropriate for specimen purposes, not to be set in jewellery. This is only a general comment because there are opals from these countries that have not cracked but you have to be very careful because they may in time.
Are all Australian black opals free from the problems of cracking or crazing? No, just because it is from Australia, even from Lightning Ridge which has the best reputation for secure stones, there are some mines that produce gems that are not secure. Only deal with reputable opal merchants with many years of experience because unscrupulous dealers will try to sell you an insecure opal for a top price. Cracking is not a big problem but it does exist.
Is there any particular shape that is preferable in black opal? Well, the traditional shape for black opal is oval with a high dome, and this has resulted in a lot of good quality opal being wasted because cutting an oval out of a piece of rough opal is not very economical. In recent years the public has woken up to the fact that free-form black opals are just as, if not more interesting to look at as the ovals.
What is an opal undulate? Well, you won’t hear that expression used anywhere else but from this writer, as it was more or less invented by myself to cover an area of opal finishing that has not been addressed, as far as I know. In recent years to save wastage of a gemstone that is fast becoming extinct, the practice has been to use dental drills to clean up the surface of the black opal by removing any imperfections, thus creating a stone with ‘hills’ and ‘valleys’ or ‘undulations. These pieces are really magnificent and I have applied this term to describe them.
Where can I find out more about black opals? You can access the opal encyclopedia at opalmine.com where you will find, not just a discussion of black opals but of all the other types of opal too, as well as the industry, the people, the surroundings, the mines that are associated with them. You might even find inspiration to visit these places and search for black opal yourself.