This opal is 9mmx 7.25mm and weighs 1.35 carats. It's a rectangular cushion and I think would be best set as a pendant, since opal is a bit on the fragile side. Under fluorescent lighting it only shows a bit of fire, but get it out in the sunlight and it just goes crazy. Red, Orange, Yellow, Green and even some Turquoise Blue can be seen in it's depths. A very attractive stone for those who like to play with fire !