Is it possible to turn carbon into diamond?

The short answer is yes.

The BBC demonstrated is a couple of weeks ago. OK they were not much bigger than grains of sand, but changing the allotropic form of carbon is possible. Watch the video.

Actually it happens all the time. It's not that hard to do it. There are several industries that rely on diamond (synthetic) cutting materials. De Beers happens to have a stranglehold on the diamond industry and they control both the supply and demand (and the lawmakers that say whether or not synthetic diamonds can be sold).

http://www.shelbygemfactory.com/

I've also heard that there's a company in Chicago that can make diamonds out of carbon extracted from cremains. Imagine wearing your grandmother as jewelry.

No, not done commercially, because the cost of equipment needed to make the transformation would outweigh the profit unless it was used over VERY long term. If the aforementioned equipment broke, you would be looking at a hefty bill of repair.

Yes it is done,needs extraordinarily high pessure and temperature.Isam not sure ,but think it is, or was, done commercially.

Yes it is possible but only if ur Billionaire or have a personal Genie¡¡¡

The answer is elementary.