Ah-tet-inbyae (Open Pit), Kyauk-Pyat-That, Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar
The joint venture concession is located next to the Sate-inn-loo mine. It is situated in a natural crevice leading to a series of interconnected caves. The main cave is 50 meters high, of varying width at its base. Mostly rubies and spinels were found in different types of marble along the walls of the main cave. Rubies, sapphires, color-change sapphires, spinels, schorl and other gems are also found in the loos (twisted holes). The color-change sapphires appear bluish in fluorescent light, shifting to reddish-pink in incandescent light. The largest ruby found here was 57 ct, fully transparent, silky, without cracks. Large, low quality cabochon-grade sapphires, sometimes weighing half a kilogram, were frequently found.Due to disputed ownership of the mine, its entrance was blocked with large boulders and the mine was closed.
Ref: Ted Themelis (2008) Gems and Mines of Mogok, p. 262