Gemstones are minerals, but not all minerals are gemstones. Gemstones are minerals that have been cut, polished and made into jewelry. Many gemstones are actually the same mineral under different conditions, changing the physical appearance. An example of this are rubies and sapphires. These gems are from the mineral corundum and are identical except for color. The above crystal cluster is quartz. A wide range of quartz gems include amethyst, aventurine, citrine, smoky quartz, rose quartz, and chalcedony. There is a rainbow range of colors in the quartz family.