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