Navajo Sterling Silver Ring with Gorgeous Turquoise Size 7

Vintage Navajo sterling silver ring set with a gorgeous turquoise stone. It has deep blue Nodules and rusty brown matrix. Very special stone! Stone is set in a plain bezel and has twisted wire rope and a scalloped frame. There are scratch marks inside of every scallop. I wonder if someone cleaned out old silver polish with a sharp object? 

Face measures 1 3/8" long by 1" wide. It weighs 11.6 grams. No hallmarks. Acid tested. C. 1960.