Specialists exist for a reason. For this retail worker , jewelry is their career. They're a diamond specialist who works at a privately owned business. Even though they have impressive expertise at their job, there are always customers who think they know better than a trained professional. Something customers don't seem to realize is that expertise matters. As a customer, you go to see someone who's spent 10,000 hours learning a trade because they have knowledge that you require. That's the wh…