There are several semi-precious stones which are used as gemstones in the crystal form or in the form they are mainly mined in. However, most actually still have to be cut and then polished before using them as gemstones for jewelry, accessories and other ornaments and adornments. There are basically two main types: the first would be the stones which are cut as smooth and dome-shaped stones that are called cabochons; and the second one would be those stones which are cut using a faceting machine to polish small flat windows or facets at regular intervals.

Those semi-precious stones that are opaque like turquoise, opal, variscite and others are typically cut as cabochons. These are generally designed to show the color of the stone or the beautiful properties of the surface like in star sapphires and opals. Equipment like polishing agents and grinding wheels are basically used for the grinding, shaping and polishing to attain the stone's smooth dome shape.

On the other hand, gemstones that are transparent are typically faceted. This is a method that would make sure that the stone's interior's optical properties are shown to its maximum advantage, as the sparkle or the reflected light seen by viewers is maximized.

There are a lot of shapes that are commonly used for faceted stones. Facets have to be cut at exactly the proper angles, and this would vary depending on the gemstone's optical properties. Angles must not be too shallow or too steep, as light may pass through and not be properly reflected to the viewer. A faceting machine is normally used to hold the stone flat for accurate cutting and efficient polishing.