Lab grown diamonds or man-made diamonds are the diamonds made of the same material as natural/mined diamonds, they have the same physical, chemical & optical composition as naturally occurring ones. Everything is same between lab grown diamonds and the naturally occurring diamonds except for one thing: Their origins.
The diamonds are created and cultured in laboratories whereas on the other hand natural diamonds are extracted deep from the Earth.
The creation of our diamonds, lab grown, does not affect the environment in any possible way, but naturally extracted diamonds require to dig deeper into the earth which causes irreparable loss to the environment and this evokes many harmful effects on our dear planet.