Like most of the people in the artificial diamond industry, they either were bought out, threatened and changed their process, or were killed.
EDIT: Actually, looks like they went out of business. I'm betting execution didn't match promises.
Artificial gems that try to pass as "real" diamonds have to commit a lot of forgery, not just at the molecular level. Forging the mining certificates, the registration (with GIA, IGS, or other certification services) which actually look at when and where this diamond was mined, etc.
Even if you could perfectly recreate diamonds, you'd find very quickly that selling them for anything other than industrial purposes would be a huge challenge. Jewelers and distributors don't want to piss off DeBeers. Anyone showing up with any kind of volume and quality product that has gone "around" DeBeers somehow would raise far more suspicion than it's worth.
Source: I worked in the jewelry industry for 2 years, and we occasionally had people try and sell us unmarked/unrated diamonds. Totally not worth the trouble.
Gemesis is the company mentioned in the article and they still exist. You can buy lab diamonds from their website, even. Of course, they haven't transformed the industry because they are profit motivated, so they just sell their diamonds at 20-30% off rather than at their marginal cost to produce or something.
DeBeers only controls about 35% of the diamond market today, a far cry from the 80% of sales they controlled in the 1990s [1]. There are good reasons to avoid unmarked diamonds but posting of DeBeers isn't one of them.
http://www.wired.com/wired/archive/11.09/diamond_pr.html