they will not increase over time, and there is a ton of market proof to show that, going back to the 1980s. e.g. https://www.theatlantic.com/magazine/archive/

they will not increase over time, and there is a ton of market proof to show that, going back to the 1980s. e.g. https://www.theatlantic.com/magazine/archive/1982/02/have-you-ever-tried-to-sell-a-diamond/304575/ https://www.theatlantic.com/magazine/archive/1982/02/have-yo... (spoiler: it's harder to do than you'd think, and you won't get anything near what you pay -- and that in the 80s, before synthetic diamonds pushed the market down further)