Friendship, love and loyalty are represented by this historic celtic design. A London Topaz claddagh ring with your birthstone or favorite color makes it even more significant. The birthstone of December, the intense deep blue color of a london blue topaz ring can evoke thoughts of warm Caribbean nights. 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.