London Blue Topaz & Diamond Arrow Flat Back 9k Gold This flat back earring showcases the unique beauty of the London Blue Topaz gemstone enhanced by a super shiny delicate diamond arrow detail. A perfect investment in both fashion and quality. London Blue Topaz is known as the jewel of love and loyalty. It represents everlasting love and friendship. Diamonds are April's birthstone but also known to be a symbol of purity and absolute truth.