Yet when you do the training to work in it, they insist for quite a while that they make more money per square foot than diamond merchant.

Don't kid yourself, it's not because you can visit for free that the whole thing isn't design to extract the most money possible...

Of course they gross more money than a jewelry store. That sounds impressive, but really isn't if you think about it. They sell very popular items that almost everyone in any mall in the country owns some version of that people WANT to buy every few years at most(computer, phone, headphones). Jewelry stores sell items that a lot of people will never own, and they sell items that people might buy every 5 years if they are really good customers.