Is it true its hard to tell a Russian Lab diamond from the real thing?

By Russian Lab diamonds, do you mean the ones that are made "synthetically," but in the original, natural way (compressing an amount of carbon)?

I remember a while back on PBS, there was a NOVA episode where they talked about these synthetic, but real-looking diamonds (I don't remember if they were Russian).

Here's a site from the Russian labs themselves (although I guess it's hard to tell if it's just marketing or otherwise): Synthetic Diamonds, Diamond Synthetic, Cultivated Diamond,Simulated Diamond Jewelry and More

Here's a good consumer report magazine article:
Wired 11.09: The New Diamond Age


Good luck!