I saw an interesting documentary a little while ago that was all about the DeBeers response to the growth in artificial diamonds.
They are developing / have developed an array of techniques that can distinguish natural diamonds from artificial ones.
Despite being basically the same material the artificial ones have a different distribution of impurities in the carbon matrix; something that can be detected by careful examination under coloured polarised light, conductivity tests, spectral analysis of fluorescence etc. Needless to say the machines for performing these tests aren’t cheap.
DeBeers has initiated something it calls the “Gem Defensive Programme” which is providing such detection machines to jewelers alongside a campaign to promote the use of natural stones rather than “fake” ones. Wired article. It’s also spearheading the research into detecting the synthetic stones.
It’s likely that DeBeers, via the DTC, will also be putting pressure on the sightholders (companies authorised to buy rough diamonds from DeBeers - a list of only 84 worldwide) to refuse to deal with synthetics. Sightholders pretty much have to take what DeBeers gives them and, until synthetic production can begin to match demand, they won’t jeopardise their supply. This means that for gem quality synthetics to break into the market they will probably have to go through other channels of distribution, dealing and cutting, increasing their price and decreasing their availability.
Pearls, these days, are almost always cultured rather than natural. Natural ones are worth more due to their rarity, but look and feel exactly the same as the cultured ones.
Pretty much the only way to settle a dispute over the origin of a pearl is with an x-ray machine, and even that is not guaranteed since it relies on spotting the smooth, spherical seed used in culturing from the random grit found at the centre of natural ones. There’s no reason that a pearl farm couldn’t use more natural looking seeds other than the economic fact that it would reduce the yield of perfect, spherical (and therefore valuable) pearls. In this case cultured pearls would be pretty much undetectable.
DeBeers is going to fight like hell to maintain their monopoly for the forseeable future, using whatever scientific and marketing methods they can. I think they may have to since they have billions of dollars of diamonds in reserve at the moment, waiting for more favourable market conditions - stock that has been bought but which has not yet turned a profit. If the price of all diamonds collapses it may seriously affect their financial future.