Sterling Silver Labradorite Pietersite? Ring

Marquise shape sterling silver ring is marked 925 and features a black and blue stone that is either a Labradorite or a Pietersite, and a small, approximately 4mm round faceted stone which I believe is a Blue Topaz.  The ring measures a ring size 7 1/4 and the face of the ring measures a little over 1 inch long.  The stone is very pretty with flash and iridescence in the lighter area.