Silvery Blue Osmena Pearl Earrings and Ring

The screw earrings and ring are a beautiful silvery blue.  The shell is from the center of the chambered nautilus.  They are all in excellent condition.  They are set in what appears to be sterling silver, but they are not marked.  They measure 1 1/8" x 3/4" and are 1/2" high. The ring is 5 3/4.