A. E. W. Mason 
The Sapphire 

It follows a Sapphire given to a Captain Michael Crowther by his Burmese wife who he is deserting. When he finally decides to return to them he finds them now out of his reach and so he becomes a Buddhist Monk. However, the Sapphire that now adorns a temple is stolen and so begins an adventure to track down the missing gem.
Love and adventure followed Sapphire’s trail across half the world…