 | In 1987, gems were discovered in the Luc Yen area of Vietnam’s Yen Bai province. Ruby, sapphire, and spinel from primary and secondary deposits are the most valuable. Tourmaline, gem-quality feldspar, pargasite, and humite are also mined there. As a result of this discovery, the Luc Yen district has become Vietnam’s most important gemstone-trading center over the past 30 years. The Luc Yen district mainly consists of jungle-covered karsts separated by several narrow valleys where paddy fields and traditional villages are located. |  |
 | It is bordered on the west, south, and east by Thac Ba Lake. The lake was created in 1970 by the construction of a dam for Vietnam’s first hydroelectric power plant. Thac Ba Lake is 80 km long and contains more than a thousand islands. |  Covering the area between Tan Huong and the Luc Yen peninsula, it submerged a gem-rich area. |
 Cluster of red spinel octahedrons on the marble-host from Luc Yen, Vietnam | Vietnamese spinel was initially found at Luc Yen but today, Yen Bai is the only active source. The newest deposit, found in February 2010, is Lang Chap, notable for its orange-red padparadscha-like stones. The most productive spinel deposit remains the old Cong Troi mine in An Phu, which yields a wide range of colours. |  |
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 | A local gem market is held in the town of Luc Yen every morning at 8 o'clock, where local production of gems and minerals is available for sale. |  |
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