One 18 karat yellow gold ring designed by Christopher Michael set with one 2.31 carats rectangular tourmaline, green/red bi-color, cut grade very good, measuring 4.3 mm wide, 16 mm long, 3.5 mm deep with VS clarity. Aracuai Mine in the State of Minas Gerais Brazil. The overall quality rating of this tourmaline is 889 out of 1000.  Ring weighs 7.86 grams.