From the article:

>The arrival of lab-grown diamonds has challenged the widely-held assumption that diamond prices could only go up

I'll admit I don't know a lot about the diamond market and perhaps I'm misinformed, but how on earth was this a widely held assumption? In a world where people are increasingly aware that De Beers and other companies hold major stockpiles of diamonds solely to keep the price inflated, and when man made diamonds for industrial purposes have been a thing for a long time?