Lab created gemstones are made of the same mineral composition as natural gemstones, and are created in laboratories with equipment that simulates the high pressures and heat that nature used to created the real gemstones far beneath the surface of the earth. A lab created gemstone is identical to the natural gemstone it replicates in every way; color, hardness, composition, luster, looks etc.
The only difference between a lab created gemstone and a natural gemstone is that the natural gemstone most likely has flaws called inclusions, and lab created gemstones have no inclusions, as the mineral composition, heat, and pressure are controlled in the laboratory. Having no inclusions in a perfect lab created gemstone sounds favorable, however too perfect can sometimes look unnatural or phony.
The flaws or inclusions in natural gemstones are caused by minute traces of minerals that are trapped within the gemstone during the gemstone's crystallization process, and are the result of certain extraneous gases and other minerals being mixed in the molten mass prior to its cooling and crystallization. Natural gemstones with fewer inclusions are given a higher clarity rating, and thus a higher value when being appraised.
It’s a head scratcher when comparing the price of a lab created gemstone which is flawless, against a natural gemstone which has inclusions, that we would knowingly pay for a natural gemstone, many multiples of the price of an identical flawless lab created gemstone, but this is a result of our culture, and the jewelry industries marketing efforts. Remember a lab created gemstone is identical to a natural gemstone, except that the lab created gemstone is flawless. Because of the high price of natural gemstones many gemstones sold today are lab created.