If Gold had to pick a fun part of his job (and he was not, for the record, much of a thrill of fun seeker) this might very well be it. When someone found something they quite liked enough to get a certain expression.
On the other hand, he also sometimes like ripping people off. And kicking teenagers out of his shop. And closing an hour early, because he owned this shit, and he could totally do that if he wanted.
The point was, he was pleased. In some regard. He lifted the watch out by its' chain and handed it to her to look at. "You've a good eye, dearie. Waltham model, dates back to the early 1900."