This principle is a bit like the "crystal" concept in business. It does not refer to the natural crystals that we are familiar with, but a special type of bright glass used in artificial jewelry. For example, the crystal cups and crystal lamps we often say are not cups and lamps made of natural crystal, but synthetic glass. Because of the addition of metal elements, the performance of this kind of glass is better than that of natural glass. One of the most typical examples is Swarovski crystals. Swarovski crystals are actually lead glass, which is particularly bright because of the addition of lead.
Therefore, Swarovski crystals are considered the best among rhinestones, with excellent cuts and dazzling brilliance. But don't say that Swarovski sells fakes. People never say that they sell natural crystals. Its selling point is craftsmanship and design.
It's just that merchants will blur this concept when selling in the market, making people mistakenly think that this is a natural crystal or even a real diamond.