|Colemanite||NMNH G4941-00||California, United States||14.85 ct|
|Sinhalite||NMNH G3548-00||Sri Lanka||43.5 ct|
|Hambergite||NMNH G8817-00||Betafo Dist., Madagascar||5.93 ct|
|Jeremejevite||NMNH G8456-00||Namibia||3 ct|
Colemanite (bottom right) is one of the main sources of boron, and although gems such as this 14.9ct stone from Boron, California, are too soft to use in jewelry, they provide an interesting challenge for a skilled gem cutter. Sinhalite gems such as this huge 43.5ct yellowish stone (top) from Sri Lanka were once thought to be a variety of peridot. They were recognized as a distinct mineral in 1952 and named for the major source, Sinhala, the Sanskrit name for Sri Lanka. Also shown are a 5.9ct hambergite from Madagascar (left) and a light blue 2.98ct jeremejevite from Namibia (bottom).
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