At some point in the near future, maybe 1 year, maybe 10, anyone with a spare couple million dollars will be able to buy a machine to grow diamonds indistinguishable from mined diamonds, defects and all. No one will be able to tell at all, and the market will be flooded. Prices for mined & manufactured alike will crater.
The price of a basic CVD system is already much lower than that.[1] The process is slow, though. Weeks of time in the vacuum chamber with vapor being deposited one layer of atoms at a time.
There is no future for mined diamonds.