Synthetic diamonds definitely need a marketing glow up. Current names are man-made, lab grown, and synthetic diamonds. Instead we could lean into how cool the HPHT and CVD processes are and have - giga forged diamonds (gigapascal pressure of HPHT), plasma coalesced diamonds (CVD process), or even human forged diamonds (highlighting technological triumph required to achieve these).
Humans seem to have a bias against "unnatural" language. Synthetic, artificial, man-made, these all evoke negative emotions in most people unfortunately.