In 1902, the French chemist Auguste Verneuil developed a process for producing synthetic gemstones.Chemical dopants can be added to create artificial versions of the Ruby, all the natural colours of Sapphire, and in addition, other colours never seen in geological samples. Stones created in a lab are chemically, physically and optically identical to those mined underground, yet they have fewer flaws and cost less, too. The more expensive and hard-to-find natural gems, such as sapphires, emeralds, and rubies are favourite lab-created stones.
Created stones are also called synthetic, cultured or lab-grown. Where I know gems to be such, I always clearly name them so.
To the untrained eye, there are a few clues that a stone may not be natural; created stones are made in a controlled process that minimizes internal flaws. This is not to say that a flawless gem is necessarily artificial, but if such a stone is natural, it will be very expensive. Big natural precious gems are a rarity, and they are very pricey. If a stone is relatively cheap despite having few flaws, being big, and having an intense colour, then this is a clue that the stone might be lab-created.
You will not find Cubic Zirconia in this collection except as accent stones or haloes; if you are looking for the Diamond simulant, please check the Stone Set collections.