Earlier quoted context omitted.
The whole point is to spend money and to be an honest signal https://en.m.wikipedia.org/wiki/Signalling_theory In the event artificial diamonds are genuinely indistinguishable from natural ones they will all, natural and artificial, become worthless aside from practical applications.
That's a really, really dim signal though, right? You literally need a microscope to see the signal.
Brands will make themselves known as the more expensive option. People don’t give cubic zirconia engagement rings as is because they’ll look cheap if they’re honest and be outed as a cheap fraud if it’s found out that it’s not a diamond when they pretended it was.
De Beers will find a way to make aspects of the jewellery other than the gem identifiably theirs. Then when you’re caught pretending a $100 lab diamond ring is a $6,000 natural diamond De fBeers ring you’ll be in just as much trouble as if you’ve given them a cubic zirconia.