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. November's birthstone, citrine sparkles like honey. Carry the warmth and glow of a golden sunset with you by wearing a beautiful citrine ring. The birthstone of December, the intense deep blue color of a london blue topaz ring can evoke thoughts of warm Caribbean nights.