The principle mines are located in the north side of the Mogok-Mandalay road.
In 2001 the gems were mined in open-pit schemes. Rubies
of all qualities and sizes, usually small, are found in the alluvium with red, pink and green spinels
. Few high quality and large size blue sapphires
are recovered. The principle rocks are quartzite, leucogranite and marble.
During 1997-1999 mining period rubies and sapphires were mined in numerous lebin
The largest sapphire found in Gwebin weighed about 200 ct and was of good quality and faceting grade.
Ref: Ted Themelis (2008) Gems and Mines of Mogok, p. 265