Sterling Silver Blue Topaz and CZ Halo Necklace. This classic halo 18 inch necklace features a 6mm genuine round blue topaz surrounded by a halo of .22cttw of simulated diamonds. Comes with an 18 inch platinum bonded sterling silver cable chain. All stones are set in platinum bonded sterling silver and come with a full lifetime warranty. Covers any and all stone loss, plating wear or breakage.