The origin of the name "rhinestone" comes from rock crystal that were found near the Rhine River in Austria. There were only small amounts of these crystals available, and as a result, they were viewed as precious and became expensive. During this time, these crystals were cut and finished by hand. Real rhinestones were rock crystals found near the Rhine River in Austria.
Enter Georg Friedrich Strass. Georg is considered to be the inventor of the rhinestone we know today. He increased their availability around 1775 by developing a technique of imitating diamonds by taking lead glass, and coating the lower side of it with metal powder. Classic rhinestones had a metal powder coating on the lower/bottom. Rhinestones are generally made from crystal, but some are made of glass or acrylic.