Fire-opals come from Mexico, and they range in colour from a fine clear orange, as here, to a milky colour similar to moonstone, sometimes with opal-like flashes. It's a very attractive gem-stone with which most people are unfamiliar, but it is a colour that is not found in any other stone. The opal is very well cut and lively. Stamped inside the shank is 1.81 which I take to be the weight of the opal. It is set with around one carat of diamonds, the shank stamped 14K, so probably American, also AMI the unknown maker. A very attractive and unusual ring. English size L : American size 5 3/4 which is fairly standard, but it is easily sized.