Item Number: 149 Shape: Oval Category: Black Colours: Blue and Green Weight in carats: 3.9 Dimensions in millimeters: 13.5 x 9.25 Thickness (mm): 4.75 Classification: Solid A dark stone with rich colours. Suit a ring or pendant. This is a classy black opal. Suits white gold or yellow gold. 18 K would be best and diamonds as well!