Chain of gold
“But even if responsible, ethical mining is possible, verifying it will be difficult even with the best of intentions, industry experts say. Diamonds, furs and timber all look simple by comparison, because they all come in a discrete form that can be tracked by a paper trail. A specific tree produces a specific two-by-four; a diamond comes from one mine that can be found on a map. Gold is not like that. It must be purified and smelted, amalgamated and combined into forms that jewelry makers can then use. That means many more steps on the journey from mine to display case, and no easy trail to follow.” New York Times, “With This Ethical Ring I Thee Wed”