Mexican Fire Opals are considered some of the most beautiful opals in its species. There are three species of opals: precious opal, fire or red yellow opal and common opal. Each species has its own characteristics. “Mexican fire opal can have a water clear base, any degree of yellow to orange to deep red-brown, white and very rarely seen…and perhaps only rumored…black”, as described by Paul B. Downing, Ph.D in his book Opal Identification & Value.
Today, Mexican residents still search the stone quarries looking for this very distinctive stone. It is believed that Mexicans gave fire opals their name and is not surprising that fire opals are Mexico’s national stone. Fire opals are not only found in Mexico, but in Brazil, Tanzania, Ethiopia, Mali, Guatemala, Canada and Turkey.
Fire opals are either faceted or cut into a cabochon shape. A cabochon cut tends to show its rich warm glow of color more than a faceted stone. The opal is a 6 to 6 ½ out of 10 on the Mohs scale of hardness. For that reason, it is not easy to cut. When cutting and later setting, care needs to be taken that the opal does not come into contact with heat as it will dry out the stone or cause it to crack.
When raw stones are found, they are generally found with a white weathering crust. This shows that the stone has dried naturally vs. artificially, and may be more durable. Only an opal specialist can speculate as to the durability of any raw stone find. The rule is the drier the environment of the fire opal, the more durable it is.
It is probably not a good idea to wear a Mexican fire opal ring or bracelet everyday although opals like moisture from the skin and air. You may want to keep out of the sunlight for extended periods of time. One trait that all opals have in common is that they are made up of 3% to 30% water. Opals are susceptible to chemicals, sharp objects, cosmetics and perfume. They are not meant to be cleaned in an ultrasonic as the heat and chemical solution are harmful.