A couple comes in together (let's call them Mike and Stephanie). Mike is ready to spend about $20k, which is a LOT of money for a young couple, and I'm showing them rings in that range, but Stephanie keeps pushing for more, and more, and MORE. Finally, with enough begging, pleading, smiles, and thinly veiled sexual promises, she talks him into a 3 carat center diamond, with an elaborate setting, for around $30k. Honestly, I don't feel great about having to witness this whole exchange, but at the end of the day, it's none of my business, so I complete the transaction.
About 3 weeks later, Stephanie comes to my office alone. I assume she needs the ring re-sized or something, but instead she asks me if I can remove the center diamond and replace it with a CZ (cubic zirconia, a very cheap diamond substitute). I'm surprised, so I stammer "sure, but why? Are you traveling or something and don't want to risk the stone?" She responds that it's nothing like that, she just prefers to have the CZ in there for now.
Obviously, every red flag in existence is waving in front of my eyes at this point, so I say OK, take her ring, and tell her she can come back in a day or two to pick it up with the CZ in it. But as soon as she's out the door, I'm dialing Mike. After all, HE'S the one who wrote me a $30k check, so HE'S my customer, not HER. Mike picks up, and after a moment of small talk, I ask him if he knows what Stephanie is up to. "NO!" is the shocked response.
Mike called me back the next day and told me that apparently Stephanie was planning to call off the engagement and return the ring, but keep the 3 carat diamond. He was obviously very upset, and asked me if I could give him a refund. I offered my sympathy, and gave him back his money. Needless to say, he was very grateful that I had called him.
About 2 years later, Mike came back with another woman who I liked much better. They're happily married with two kids now. Mike and I have become friends, and he's probably referred me 10+ other customers over the years. As for Stephanie, after she left my office that day, I never saw her again.