Hi Linda,
 
I just ran downstairs and asked my son about this, as he works at a jewelry store.  He said there are cultured pearls, but he has never heard of "cultured diamonds."  Since I bought lab-created sapphire necklaces (when his store had a sale) for my 3 granddaughters for Christmas, I asked him if perhaps you were talking about lab-created diamonds.
 
He said there are lab-created diamonds called Moissanite (I think I spelled that right).  He said they test like diamonds although at a little different light frequency, or something like that. I voiced my opinions about conflict diamonds, and he said their company, Kay Jewelers, doesn't buy conflict diamonds, but from de Beers, who have their own Kimberly mines, and pay their help well.
 
Then I brought up that perhaps there was a big price difference, but he said, "actually there isn't much difference."  He said personally he wouldn't buy a Moissanite diamond, but rather a real one instead, when the time comes.
 
I hope this info helps you.  If in fact some store is actually selling "Cultured" diamonds, that my son has never heard of--I'd walk away.  But, if dealing with a reputable jeweler, at least now you have the info about natural diamonds and lab-created ones, and hopefully can make a more informed decision.
 
God Bless,
 
Kay