Necklace Collection : One of a Kind Tanzanite with Opals necklace by Irene Neuwirth. 51.75 carats of t… 6 June 2018 3116 Necklace Collection : One of a Kind Tanzanite with Opals necklace by Irene Neuwirth. 51.75 carats of tanzanites with Lightning Ridge opals in 18k rose gold.