Aside from the eight-pointed cross in his lapel, the only ornamentation or jewelry he wore consisted of a small, exquisitely thin gold watch on his left wrist, and, on the ring finger of his left hand, a gold signet ring set with a single, flat, unfaceted diamond which was delicately engraved with the Tarnhorst coat of arms.
"Anchorite"
Randall Garrett
And it's unfaceted, to eliminate offensive flash.
"Anchorite"
Randall Garrett