Saw a documentary on PBS (of all places!) once about the DeBeers monopoly, and how they bribe, or do whatever they have to in order to maintain that monopoly, and to push the fairy tale that diamonds are either rare, or have any real value.
Why don’t jewelry stores sell used stuff? SURELY it could be cleaned up, and resold, right? That is, unless the diamonds really are mostly worthless trinkets marked up by a global monopoly.
I have my husband’s great-grandmother’s diamond engagement ring. It is pretty and the diamond is good quality, however the way diamonds were cut a hundred years ago is different than modern methods. The mine cut diamond is less brilliant than a modern faceted one.