The colour of fire opal can range from yellow to red, with orange to red the most usual and red the most desirable. Fire opal usually has little colour play so the iridescent cab shown here is quite rare. Good-quality stones should be transparent with a vitreous lustre; they should not be milky or opaque. Unlike other types of opal, fire opals are often faceted like the stone below. Large transparent faceted stones with a good colour have increased in value recently, but fire opal does not realize the prices of precious opal.