Friendship, love and loyalty are represented by this historic celtic design. A Onyx claddagh ring with your birthstone or favorite color makes it even more significant. Black and gold make a beautiful and elegant combination. A black onyx ring is a perfect accessory for any outfit. Sapphire is the birthstone of September, and one of the most popular gemstones on the jewelry scene today. The deep blue color of a sapphire ring is just right for an evening out.