Dear Mr. Know-It-All, Where can you sell a diamond necklace from Tiffany’s? I have one from that evil ex of mine and I can’t bring myself to wear it anymore (on the account of hating him so much). - So Much Better Without Him You’re in luck. Circa (Suite 1422, Princes Building, 10 Chater Rd., Central, 2810-8887) is an international fine jewelry, diamonds and watch buyer. It has offices around the world and knows all about assessing and purchasing fine jewels. Contact them to schedule a private and cost-free appointment to value your tainted diamond necklace. If there is an offer and you decide to take it, it’s an immediate, commission-free payment too.