My Lab Created Diamond

In the HPHT process,  small diamonds are used as seeds. Graphite is dissolved in a molten metal at high pressure, and slowly precipitates as new diamonds.

Interestingly, the HPHT process can also be used to improve the colour of natural diamonds, changing them from brown to yellow-orange-green shades. This is a controversial process as it can be very difficult to identify natural diamonds that have had their colour improved by the HPHT process, even in the lab. Many of the labs who perform this process say that they are only restoring the natural colour of the diamond before it was discoloured in the volcanic process that carried it to the surface of the earth.

Natural diamonds treated by HPHT, if identified as such, should be significantly cheaper than the equivalent untreated diamond. Natural HPHT diamonds are required by law to be identified when sold or graded.