Vintage Silver navajo bracelet

Sterling silver and turquoise navajo cuff bracelet. Vintage, antique bracelet. Large turquoise stone with beautiful flowering silver workmanship surrounding the stone. This is a masterpiece. This piece was given to me. I was told it was purchased up north Wisconsin from an Indian trading post back in the 70s. I attempted to polish it as it was literally black with tarnish and wasn't successful with removing all of the tarnish in the small crevices. Someone with more knowledge or of profession will be successful, no doubt.