Lab Sapphire engagement rings? Absolutely! Diamonds may be a girl's best friend, but Lab Sapphire engagement rings are a unique, original, and a far more affordable choice. 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. The birthstone of May, an emerald ring symbolizes the eternally returning spring. The velvety green color of emerald is a perfect match for spring and summer fashions.