Star K Oval Simulated Blue Opal Halo Ring Sterling Silver Metal: 925 Sterling Silver. Dimensions: Width: 10.50 mm Length: 12.50 mm This beautiful design is part of the exclusive Star K. Jewelry collection. Star K, is a reputable American Family Business based in New York since 1986, uses only the highest quality materials, and will proudly stand behind all of her products. Blue Simulated Opal: The Alternate Simulated Birthstone for October. From the Greek `opallios`, meaning `colour change`. A symbol of hope and faithfulness for the rainbow locked within it, it inspires true love and brings confidence. Additional Stones: (cubic-zirconia, Shape: round-shape, Color: Colorless.)