Demantoid garnet is a calcium garnet, meaning it contains calcium as part of its chemical makeup. The most valuable color for demantoid garnet is medium to medium dark green. Most demantoid garnet is a greenish yellow to yellowish green and brownish yellow. Demantoid garnet is very rare especially in sizes over one carat. Demantoid garnet is one of the few gemstones that break up white light into its spectral colors more than a diamond, meaning you can see flashes of spectral colors coming from the stone.
Demantoid garnet was originally discovered in Russia in the mid 1800s and Russia is still considered to produce the finest demantoid garnet. Today demantoid garnet is also found in Namibia with some minor supply in Italy, Greece and Mexico. Demantoid garnet is one of the few stones that can be more valuable if it possesses a certain inclusion. Many of the stones mined in Russia have a unique feature referred to as a horse tail inclusion. A horse tail inclusion is a bunch of curved asbestos fibers radiating around a central point inside the garnet. Cutters often cut the stone to show off these inclusions.
The disadvantage of demantoid garnet is its hardness. Demantoid garnet is a 6.5 on the Moh’s scale (amethyst and citrine are a 7 rubies and sapphires are a 9). This means if you looking for a stone you can wear frequently and not worry about chipping or fracturing, demantoid garnet may not be the best choice for a ring. However, it may be set in pendants or earrings, and is an excellent choice for a unique piece of jewelry.