It's a bad example. The purchase of diamonds has always been a form of status symbol, making the decisions about it very different to those involved in purchasing common goods. Luxury goods centred around human labour will become more normal in the AI era as that is how people will come to express status - they can afford to have a real human do something.

That doesn't stop the tech being a massive disruptor.

This is a bad example but also a good illustrator - the decisions behind the price of diamonds is an indicator of how at least part of the economy will play out.