Wet-loo (Wetloo), Kyauk-Pyat-That, Mogok Township, Pyin-Oo-Lwin District, Mandalay Region, Myanmar
It is located east of Sinkwa. Rubies are mined from the alluvium using the myaw-dwin and lebin mining methods. Low quality blue sapphires weighing more than 5 ct are often found in the alluvium.Rubies and spinels are also found in the loos (twisted holes) and in the caves, characterizing the general area. Most of the rubies found in primary rock are dark red and brown-red, signifying the presence of iron and absence of fluorescence in UV light. Heat treatment generally improves the appearance of these rubies. At the nearby contact zone between marble and leucogranite gem quality painite and chatoyant painite crystals are found with ruby or spinel. Other gems found in the contact zone include rutile, diopside, chrome elbaite, schorl, yellowish and yellow-red zircons which may appear bi-colored.
Ref: Ted Themelis (2008) Gems and Mines of Mogok, p. 250