This is a Navajo jewelry piece, artist unknown. The vibrant blue color will add a pop to your fashion. The store where I purchased it explained that the stone was unearthed from the Sleeping Beauty mine. The circumference is 17cm, and the opening width is 3.2cm. There may be some slight variations, so please use this as a reference. It is adjustable. Keywords: Howard Nelson, Gary Reeves, Sunshine Reeves, Navajo Pearl, Zuni, 925 Silver, vintage, American casual