Natural Fire Opal StoneOpallios is the Greek word for Opals meaning to see a change of color. Unlike other gemstones, it is not crystalline. They can be more aptly described as a hardened jelly. Known for their special optical property called iridescence or play of colors, opals have long been known as the queen of gemstones. They can display colors with various hues and patterns, akin to an artists work. Most Opals are cut as cabochons to enhance and display this effect.