Many Enstatite stones have heavy inclusions, or materials, trapped inside. This one has very few, which is another reason for its unusually high price. Highlights: Axinite is considered a rare ...

Fine-color, large, and eye-clean (lacking visible inclusions) rubies like this 11.01carat (ct) stone from Myanmar (formerly known as Burma) are extremely rare and valuable. – Photo: Robert Weldon/GIA.

Large, vivid fancy color diamonds are extremely rare and very valuable ... Some have been fashioned into gems. The 67.50-carat Black Orloff diamond, named after the Russian Princess Nadia ...

Tanzanite is only found in northern Tanzania and is used to make ornaments. It is one of the rarest gemstones on Earth, and one local geologist estimates its supply may be entirely depleted within ...