> but customers don't for the most part. It's a lot easier than trying to explain to them that there are two kinds of ounces

It's that kind of stuff that makes people think that jewelers and gold buyers are crooked. Some customers--perhaps only a minority--do know the difference, and they will become suspicious and tell others.

Whenever a professional of any kind (car mechanic, doctor, tax preparer, vet) tells me something that is contrary to a known basic fact, then alarm bells go off in my head. I start thinking that this guy is either incompetent or trying to cheat or trick me in some way, and I will tell friends to watch out. Fortunately it doesn't happen all the time. I generally trust doctors for example.

In one of your other comments, you said, There are a staggering number of honest jewelers and gold buyers out there. But stories about obviously crooked people are what makes everyone say "see, these guys are ALL crooks".

Maybe the jewelers and gold buyers--like used car salesmen--have gotten the reputation they deserve.

And this is why I generally avoid these discussions. Someone will ALWAYS find a way to say you are wrong even when you are making an error in their favor. And for the very very few people that do know the difference, when you explain why you do it the way you do, and they will get more money for it, they tend to appreciate it. Not all, but most.