I have spent close to 10,000$ on "lab created" diamonds with Diamond Nexus over the last few years. My (now) wife wanted lab grow for many different reasons.
Lately all her jewelry had lost its luster and became dull. She had it professionally cleaned and was told (three times now by different sources) that these are simple cubic zirconia pieces.
So while they make it look good, they actual product simply doesn't hold up. Don't get sucked in by the pretty package!