Purposefully weak, to my understanding, to discourage a secondary market.

I remember an article years ago that went into detail about De Beers' manipulation of the market, and how change from "larger is better" to "clearer is better" happened just as a large mine outside of De Beers control opened that had quite a few large diamonds coming from it on a regular basis. That same article made some assertions about the secondary market being somewhat manipulated, IIRC, but this was close to a decade ago, so sourcing it might be hard, and I'm also unsure how accurate it was at this point. I think it was about how modern incarnation of idea of giving rings for marriage was also largely manipulated by De Beers.

I believe “Have you ever tried to sell a diamond” (1982) https://www.theatlantic.com/magazine/archive/1982/02/have-yo... is what you’re thinking of - it’s a great article and feel ahead of its time in style/composition.

I saw that, and it could be, but I have a (possibly false) memory of some orange-ish toned world map which showed the locations of major diamond exporters and the times they started exporting. Or maybe it was blue-ish? I think I've reached the point in trying to remember this where any additional details I might think I remember are more likely just cross-contamination of memories. :/

Could it be this one from 2013? http://blog.priceonomics.com/post/45768546804/diamonds-are-b...