How opals are painted

Noble opals of bright blue, purple-red, green colors are often found on the jewelry market. And the most amazing thing is that often such opals are of natural origin, but upon closer examination, even an inexperienced buyer may suspect something was wrong. And this is "wrong" - the base color of the opal. As a rule, opals have a natural base color in white-gray tones to black, or their range of shades is characterized from orange-red through orange and yellow to brown. Of course, there are pink, blue and green opals, but they are devoid of the effect of opalescence and even less iridescence. The stones, which, in addition to the bright color of the main background, also have additional opalescent colors with a play of iridescence, have probably undergone some kind of staining. How are opals colored? It's very simple - they place the stone in a water-soluble dye, then polish it and the colored insert is ready. The fact is that opal, having a high degree of hygroscopicity, absorbs the solution together with the dye and acquires the desired color. The second method, which is often used for transparent opals, is to make a doublet with a backing of a bright material, for example, red glass or a red synthetic ruby ​​in the backing, and the entire opal cabochon already appears red. Another way is the usual coating with dyes, which is also found. Be careful!