They pretty much are fungible with natural diamonds. High quality synthetics can't be told by eye from equivalent quality naturals.
If they're < 1ct., it doesn't pay to have them analyzed.
"Real" diamonds have always been considered scarce, but only because of marketing. De Beers, AlRosa, etc. have very large reserves of natural diamonds. Over time, they will become genuinely scarce, as the industry agrees that economically recoverable deposits of natural gems will decline after about 2020.
If they're < 1ct., it doesn't pay to have them analyzed.
"Real" diamonds have always been considered scarce, but only because of marketing. De Beers, AlRosa, etc. have very large reserves of natural diamonds. Over time, they will become genuinely scarce, as the industry agrees that economically recoverable deposits of natural gems will decline after about 2020.