From the right sellers, actual lab diamonds are also vastly cheaper than this. I'm not sure if there are consumer sources yet, but the issue certainly isn't on the supply end.
It looks rather like the startup is trying to undercut mined diamond cartel prices, but keep a hefty cut of that markup while the artificial market is still low on competition.
It looks rather like the startup is trying to undercut mined diamond cartel prices, but keep a hefty cut of that markup while the artificial market is still low on competition.