Isn’t the Russian Mafia the main producer of fake diamonds ??? Doesn’t sound too PC to me…

Isn’t the Russian Mafia the main producer of fake diamonds ??? Doesn’t sound too PC to me…

So bascially - the Russian diamonds are just as sparkly and clear - if not more so - than natural diamonds? And presumably vastly less expensive?
Is there no major advantage to natural diamonds over high grade manufactured ones other than the sentimental aspect?
If so, where can I buy the manufactured ones?