The birthstone of December, the intense deep blue color of a london blue topaz ring can evoke thoughts of warm Caribbean nights. Gem of hot summer nights and steamy red sunsets, ruby is the birthstone of July. Show the world the passions within you with a fiery ruby ring. 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.