Updated: Apr 3, 2019
Interested in learning a little more about gem formations?
Most minerals on Earth are formed when magma rises from the depths of the planet to the surface and then cools. Crystals form from chemical elements present in the liquid rock, somewhat like the way rain turns into snow crystals in the cold. Over time, the structure of some minerals changes under high pressure or high temperatures, producing new kinds of minerals in the process.
More than 3,500 different minerals have been discovered so far.
Most of them combine to form rocks, like the quartz, feldspar, and mica found in granite. The rarest and most beautiful may be turned into jewellery. This family of minerals, called gems, groups together some 50 different semiprecious stones, including agate, opal, and jade, and four precious stones. These most highly prized gems are diamond, ruby, sapphire, and emerald.