Producing diamonds out of cheap graphite looks like a good idea and at Purdue they managed to do just that.
The have found a way to transform graphite into nano diamonds by using laser pulses to hit a graphite layer. This creates a plasma of carbon atoms that is contained on site by layering a glass pane on the graphite. The fast pulsing laser is both creating a ionised carbon plasma and a pressure wave that lead to the formation of the nano diamonds.
Present technologies to convert carbon into diamond required heating the carbon to very high temperature and submitting it to high pressure. In turns this makes for a very expensive process. Hence the innovation created by Purdue researchers is about price, very low cost, and also low temperature making it possible to layer the nano diamonds on any kind of surface.
The researchers are seeing applications in a variety of fields, including biosensors, computer chips and sensors resisting to very demanding conditions (high pressures, temperatures, corrosive material exposure...).
Interestingly, they have discovered this possibility of producing nano diamond as they were looking at ways to harden a surface.
So, now you have an affordable way to create diamonds to present to your girlfriend. Unfortunately these diamonds are basically invisible to the naked eye, that's what the nano means, hence making them a tough sell if you are trying to use themas a hight tech substitute for that old fashioned diamond ring...