The process can take more than a year. Some beautiful fire opals are produced in … Smaller quantities of fire opal are produced in Australia, Brazil, Honduras and Guatemala. On the other hand, the synthetic opal with the widest range of uses occurs through the Gilson process. Fire opals have a very low density, lower than that of glass, with which it is sometimes confused. However, opals can also be created synthetically through various methods. Small fire opal pebbles can be found in silica-rich lava flows. Fire opals, like other opals, are relatively hard, rating a … Finally, they fill the pores of the structure with silica gel and harden it. Orange and yellow are a bit more common and cheaper, but these hues are still among the most expensive compared with other opal colors.

Next, they arrange the spheres in a lattice pattern to imitate the structure of precious opal. Queretaro’s mines are the most important and have been mining since 1835. The basic process of opal synthesis consists of three stages. Like the traditional opal, fire opals can occasionally display signs of iridescence in very bright light. In the 1990s, Ethiopia became an important source of opal. Some of the transparent material is faceted, mounted in commercial jewelry, and described as "tangerine opal" because of its color. Opals are naturally forming with over 95 percent of natural opals originating in Australia, which are harvested specifically from Australia’s desert areas. Transparent specimens have a good luster. When it comes to fire opals, the most valuable color is red. First, scientists create tiny silica spheres. The Mexican fire opal deposits produce significant amounts of transparent to translucent, bright orange to orange-red material. In general, the rarer the color of a gemstone, the more sought after and expensive it is.