Sterling Silver and Coral Cross Pendant - Vintage Native made cross

This vintage piece was purchased for a dear friend (actually I bought 3 crosses for her ... and this one got left behind in the decision process).  It is an exquisite piece.  2" tall (not including the loop) and 1 3/8" wide.  The coral insets are as "pure" color wise as I have ever seen.  

There appears to be a lightly scratched letter or number on the backside... or several.  I cannot really make it out and sure don't know if it was intended as a hallmark.  But as delicate at the piece is it could be that the artist did not want to attempt to stamp or deep etch the sterling on the back.  Perhaps you can solve the mystery.

It's easy to see the hand cut work when you look at the back side.  Wish I knew for sure who built this ... it is the work of a master silversmith to get this much stone, that narrow, on to this cross.