Swedish Blue found in central Sweden in old iron- ore mining areas.  Early 18th Century when smelting iron-ore this material came out in the slag.  By mid Century a more efficient way of smelting evolved and this material was no longer a by-product.  The material reminds us of the ocean and a night sky.  These rings are all silver and designed on a saddle band (think English riding saddle, smooth on top narrowing to a narrow band under the horse.  

A) 1 1/2"long x 1"wide (widest point); B) 1 1/4"long x 1"wide; C) 1 1/2"long x 3/4"wide; D) 3/4" x 3/4"; E) 1"long x 3/4"wide; F) 1 1/4"long x 1"wide.