Ammolite is an opalescent material that forms on some ammonite fossils in southern Alberta, Canada. Only about 5% of these ammonites found have suitable Ammolite material on it, and of these specimens, gem cutters can only use about 20% of the shell. All Ammolite comes from this small percentage of usable, gem-quality material, making the material extremely rare.

The iridescence of Ammolite occurs when the fossilized ammonite shell becomes mineralized- layers of thin platelets of the shell trap and reflect light, creating an array of colors to the viewer’s eyes that rivals the black opal of Australia. The layer of Ammolite on shells are typically thin and fragile, leading most Ammolite to be covered by a durable material to protect the material and maximize its presentation.