Mogok is not the only active ruby mining area in
Burma. Stones from the Mong
Hsu deposit, is located in Myanmar's Shan State, northeast of
first began appearing in Bangkok in mid 1992.
Since that time they have completely
trade in sizes of less than 3 cts.
Indeed, 99% of all the rubies traded today in Chanthaburi (Thailand) are from Mong Hsu.In
terms of quality, Mong Hsu rubies cannot compete
with Mogok stones.Before heat treatment,the Mong
Hsu ruby is certainly an "ugly stone".
two major problems with those stones:
The first is dense silk
a strong purplish color, making most stones look
like low-grade. Ordinary heat-treatment removes the blue, as
well as removing silk, making the final product
a rich, clear red.
Most Mong Hsu stones are heavily fractured.Some specialists have masked the cracking by
healing the cracks with a flux of barax...
the excellent article of R.W. Hugues