Heart Shaped Blue Opal Jewellery Set in solid sterling silver. Material: Sterling Silver. Total metal weight: 2.3 gr. Heart shaped blue opal (6 x 6 mm) = 2 ct total. Heart shaped blue opal (5 x 5 mm). Colour: Blue. Stone cut: Heart Shaped. Occasion: Mother's Day. Anniversary: 14th Anniversary. Birthstone: October.