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. Tanzanite is the new birthstone of December and has a unique purple-blue color. A tanzanite ring is one of the newest fashion trends and is a must for any jewelry collection.