GIA has studied lab-grown or manmade diamonds extensively over the past 30 years, and we know a great deal about the methods used to produce them and how they can be recognized. While synthetic diamonds are produced in factories, their chemical and physical properties correspond very closely to that of natural diamonds.

Some people might refer to lab-grown diamonds as imitations or simulants, but this is incorrect. Actual imitations like cubic zirconia or synthetic moissanite — which only look like diamond — have very different chemical and physical properties that allow trained gemologists to identify them easily. However, lab-grown diamonds are more challenging to detect.

HPHT stands for high pressure, high temperature and is one of the primary methods used to grow diamonds in a lab. This diamond growth process subjects carbon to extreme temperatures and pressures and is meant to replicate the extreme heat and pressure conditions deep within the earth where natural diamonds form.

CVD stands for chemical vapor deposition and is another method used for making diamonds in a lab. Diamonds grow from a hydrocarbon gas mixture subjected to moderate pressures and temperatures in a vacuum chamber.