Lab-grown diamonds are not simulants like CZ. They are diamonds. Instead of forming over millions of years in the earth's mantle, they are created in rough crystal form by scientists. They are optically, visually, and chemically identical to natural diamonds. Each lab-grown diamond has a laser inscribed serial number along the Girdle and is certified thru either GCAL (Gem Certification & Assurance Lab, IGI (International Gemological Institute), GIA (Gemological Institute of America Inc).