Ammolite is an opalescent material that forms on some ammonite fossils in southern Alberta, Canada along the Rocky Mountain Range. 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.

Ammonites were Cephalopods sharing a common ancestor with the squid and octopus. The ammonites that appeared in the Devonian became very diverse and widespread in the Paleozoic and Mesozoic before going extinct along with the dinosaurs at the end of the Cretaceous period. The goniatites lived early in the Devonian period, some 400 million years ago, and became extinct during the Permian period.