Most pieces of fine jewelry are just minerals in disguise, their rough edges having been cut and polished to make them presentable at dinner parties, weddings, and other social occasions. We call such minerals gemstones. Sometimes, though, minerals are appreciated for their free-form, natural beauty, which often means clusters of colorful crystals growing from schist and other metamorphic rocks. We call such minerals dust collectors.
While budding geologists have been known to amass boxes upon boxes of rocks and minerals in an effort to collect one of each, typically to the dismay of their loved ones, most people gravitate to the dramatic minerals, be it a sparkling quartz crystal, a seductive slice of agate, or a mysterious thunder egg, which, when cleaved and polished, reveals a world of wonder within its hard interior. Geodes are also sliced or cracked to showcase the clusters of pyramidal amethysts and other crystals inside, in some cases exposing these formations to the elements for the first time in a million years.
Of the almost 4,000 minerals known to exist, only about 50 are used to make gemstones. The rarest of these—labeled precious—include diamonds, rubies, emeralds, and sapphires. Minerals that are made into precious gemstones tend to be hard, allowing gemcutters to shape a stone into multifaceted jewel that can be fitted into rings, pendants, and earrings. Softer, semi-precious stones such as turquoise are usually formed into cabochons, which are rounded on the top and flat on the bottom.