Tanzanite engagement rings? Absolutely! Diamonds may be a girl's best friend, but Tanzanite engagement rings are a unique, original, and a far more affordable choice. 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. Pink tourmaline is a birthstone of October, along with opal, and is a truly special gem. The deep rosy color of a pink tourmaline ring will be sure to attract attention.