A martini, a Manhattan or a Moscow mule- whichever your favorite cocktail- deserves a matching cocktail ring and this is the one! The deep, velvety blue, oval tanzanite is set in a bold, platinum, bombé mounting with three round diamonds on each of the four sides. Over time, and while being thoroughly enjoyed, the platinum will develop a distinctive patina which is one of the unique characteristics of this noble metal. Make this your signature ring for a fun night out or an elegant event- it…