Smoky Quartz engagement rings? Absolutely! Diamonds may be a girl's best friend, but Smoky Quartz engagement rings are a unique, original, and a far more affordable choice. Brown gemstones are gaining in popularity and smoky quartz is an affordable choice. A smoky quartz ring goes well with autumn colors and evening wear. 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.