Sometimes the best designs are the simplest designs. These rings focus on the beauty and brilliance of the gemstones and the sheen of the 14K gold that encompasses them. 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. 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.