ated in 1970 by the construction of a dam for Vietnam’s
first hydroelectric power plant. Thac Ba Lake
is 80 km long, with a maximum width of 10 km, and
contains more than a thousand islands. Covering the
expanse between Tan Huong and the Luc Yen peninsula,
it has submerged a potentially gem-rich area.
The initial discovery of high-quality Vietnamese
rubies occurred in the Luc Yen district in late 1987,
after farmers recovered the stones from placers. The
ruby was found in colluvial and alluvial sediments,
and the primary source was believed to be marble.
Gem exploitation began in earnest in June 1988, with