Ammolite, sometimes also (incorrectly) called Ammonite, is by considered by some to be one of the rarest gemstones on the planet. Ammolite, similar to Opal, exhibits play of color, and is quite desirable for this reason. Ammolite is organic in nature and is not really a mineral or stone of any kind and is in fact formed from the remains of fossilized shells.
Etymology & Sources
Ammolite derives its name from the group of extinct marine animals known as Ammonites, and are formed from the remains of the shells of these creatures. Due to the similarity of the names, the gem variety is also sometimes referred to by the animal’s name. Ammonite is quite rare and is primarily found and commercially supplied from Alberta, Canada. The vast majority of Ammolite mining is performed by Korite International, and it is speculated that the supply from known Ammolite mines will run dry in the next two decades.
Ammolite exhibits iridescence that is very similar to that of Opal (although the scientific reasoning for the effect is different for the two stones). Thanks to its iridescence, Ammolite can display a wide range of colors, although it largely depends on the individual stone, with some gemstones displaying the color play effect to a large degree, and some gemstones less so. Ammolite can have a resinous or vitreous luster, and is an opaque gemstone.
Ammolite lacks hardness and scores roughly a 4 on the Mohs scale. It has a specific gravity of approximately 2.8 and a refractive index level of somewhere between 1.52-1.68
Ammolite is most often cut freeform, and can be very valuable when cut into other more desirable shapes. Ammolite basically never used in jewelry as-is – it is far too soft for this use, and it is the norm for the gemstone to be used to produce doublets (or triplets), meaning that it is attached to a harder and more common backing material to prevent damage to the gemstone. In doublet or triplet form, Ammolite can be used for jewelry of all kinds, and is popular in pendants and rings, although rings are not really advisable due to the material’s fragility.
As mentioned earlier, when Ammolite is used for jewelry, it is basically always treated in some way, and most typically doublets or triplets are created from the material to act as a protective measure to the valuable gemstone material. Ammolite is also sometimes stabilized with a synthetic resin to prevent flaking in the gemstone; this process gives Ammolite much better durability. Ammolite is virtually never sold in jewelry untreated; buyers should just attempt make sure that all treatments are fully disclosed.