Lapis lazuli is one of the oldest of all gems, with a history stretching back some 7000 years or more. This mineral is important not just as a gem, but also as a pigment, for ultramarine is produced from crushed lapis lazuli (this is why old paintings using ultramarine for their blue pigments never fade).
Color. For lapis lazuli, the finest color will be an even, intense blue, lightly dusted with small flecks of golden pyrite. There should be no white calcite veins visible to the naked eye and the pyrite should be small in size. This is because the inclusion of pyrite often produces discoloration at the edges which is not so attractive. Stones which contain too much calcite or pyrite are not as valuable.
Clarity. Lapis lazuli is essentially opaque to the naked eye. However, fine stones should possess no cracks which might lower durability.
Cut. Lapis lazuli is cut similar to other ornamental stones. Cabochons are common, as are flat polished slabs and beads. Carvings and figurines are also common.
Prices. Lapis lazuli is not an expensive stone, but truly fine material is still rare. Lower grades may sell for less than $0.25 per carat, while the superfine material may reach $1–3/ct. or more at retail.
Stone Sizes. Lapis lazuli may occur in multi-kilogram sized pieces, but top-grade lapis of even 10–20 carats cut is rare.
Name. The name lapis means stone. Lazuli is derived from the Persian lazhward, meaning blue. This is also the root of our word, azure.