Top Ten Gemstones
Poudretteite is named after the Poudrette family, operators of the quarry where the mineral was discovered. Poudrettite forms transparent violet to pink roughly equant barrel-shaped prismatic crystals. Poudretteite is a very rare material. Clean gems over 1 ct are uncommon.
Benitoite is a rare gemstone, and for all practical purposes only comes from a single limited deposit in California. It is a relatively new gemstone, and was first discovered in 1907. Benitoite gemstones have a sapphire-blue color, and can have very good transparency and luster.
In mineralogy, the name Musgravite refers to the mineral called Magnesiotaaffeite-6N’3S. It crystallizes in the trigonal system. The closely-related Magnesiotaaffeite, which crystallizes in the hexagonal system, is known in mineralogy as Magnesiotaaffeite-2N’2S.
Found in lava, meteorites, and deep in the earth’s mantle, yellow-green peridot is the extreme gem.
Most diamonds used as gemstones are basically transparent with little tint, or white diamonds. The most common impurity, nitrogen, replaces a small proportion of carbon atoms in a diamond's structure and causes a yellowish to brownish tint.
Serendibite is named after "Serendib", the old Arabic name for Sri Lanka, where the mineral was found. Serendibite forms small blue-green, blue-grey to deep blue, sometimes yellow, transparent tabular crystals.
Taaffeite Gemstones. Taaffeite (pronounced TAR-fite) is one of the rarer gemstones known, and you'll often it see on lists of the most exotic stones in the world, along with esoteric minerals such as painite, musgravite and grandidierite.
Since grandidierite is quite hard, high quality material has been cut as gemstones, making it one of the very rarest gems, in a class with varieties like benitoite, painite, taaffeite and jeremejevite. You will often see grandidierite included in lists of the 10 rarest gem varieties in the world.