Ruby engagement rings? Absolutely! Diamonds may be a girl's best friend, but Ruby engagement rings are a unique, original, and a far more affordable choice. 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.