"Ammolite" is the name for a type of fossilized mother-of-pearl, not be confused with "ammonite", which is the sea creature that lived in the shell.
Ammonites were squid-like creatures that swam the seas more than 70 million years ago during the Cretaceous period. Their shells were constructed into a unique series of air chambers that allowed them to float and move through the water using jet propulsion. Today, these complex chamber walls appear as intricate patterns in the fossils. Ammonites were abundant in all the oceans until they became extinct around the same time as the dinosaurs.
Because each gemstone is a fossil, ammolite is regarded as one of the rarest gems on earth. The preserved mother-of-pearl went through a mysterious geological and mineralization transformation, giving it light refracting characteristics that qualify it today as a precious gem. Ammolite is capable of splitting sunlight into every color imaginable, a fact that illuminates why the stone came to be known as the "Seven Color Prosperity Stone" by Feng Shui masters. Each color in ammolite represents a different layer of the gem material. So, depending on the number of fine layers in the rough, everything from one color to the full visible spectrum will be displayed. The cracking results in a mosaic appearance, sometimes described as "dragon skin" or a stained glass window pattern.
Ammolite is only found in the Bearpaw formation that extends from Alberta to Saskatchewan in Canada and to Montana in the United States. Those found in and around Alberta display the most vivid colors. Ranking 5-7 on the Mohs Scale, pricing is based on size, shape, number of colors present, brightness of those colors, and overall appearance. Each ammolite is unique and the rarest stones show three or more colors.
In 1908, a member of the National Geological Survey team found fossils of ammonite along the St. Mary's River in Alberta. It was not until 1981 that enough high-quality ammolite was discovered to make mining commercially viable. The International Commission of Colored Gemstones officially recognized it as a gemstone at that time.
Ammolite is classified as a "biogenic" gemstone, a distinction also shared with pearls, coral and amber. It refers to the process of its origin, being biological versus geological. Ammolite is commonly impregnated with a colorless hardened substance to increase stability. It has been compared to opal in that it can either be spinel-capped or a natural doublet. The spinel-capped version is very similar to the opal triplet, while the natural doublet is similar to an opal doublet.
The stone was named for Ammon, the ancient Egyptian god of life and reproduction, because the shell of the ammonite was similar in appearance to the ram-headed deity's horns. The Roman historian Pliny the Elder regarded ammolite as the holiest of stones because it was said to evoke prophetic dreams. The Blackfoot Tribe of North America came to know ammolite as the "buffalo stone", as it signified abundance, aided in the buffalo hunt and played a key role in their traditional culture and magic. Within the Chinese practice of Feng Shui, some believe ammolite gives the owner health, wealth and enlightenment. Ammolite was designated as the official gemstone in Alberta, Canada in 2004.