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. This birthstone of October has a luminosity and glow that makes an opal the treasure that it really is. The rainbow of colors on a neutral white background makes an opal ring a perfect match for any outfit.