Some gemstones.

Jewels (or gems or gemstones) are rare minerals. They usually come in colours and sizes. They begin in a rough rock form, but can be cut and polished to turn into a jewellery.

However, some other non-mineral rocks (such as lapis lazuli) or organic materials can also be also used for jewelry and are called gemstones. These include amber or jet. Pearls and coral are sometimes also called gemstones.