Vintage Mottled Green Turquoise Navajo Ring in Sterling Silver Size 6

Vintage Navajo sterling silver ring that is set with a natural turquoise stone with mottled green and turquoise color. Looks to me like it was once a lighter color and much of it darkened to greed over the years. Gorgeous color! Simple setting with a hand made shank that has a cold chisel split. Size 6. Face measures 7/8" long. Tarnished to a gunmetal gray. Needs to be cleaned. Will polish up. Weight: 5.7 grams. No hallmarks. Acid tested. C. 1950-1960s.