Only four gemstones in the world are classified as precious gemstones - emeralds, rubies, sapphires and diamonds. The term originates from ancient Greece, Rome, Egypt and Mesopotamia, where the gemstones held ceremonial and historical importance. They were named "cardinal gemstones" for their use by royalty and religious figures.

Historically, precious gemstones were valued for their extreme rarity. Large gems with fantastic colour and few inclusions were uncommon and very expensive. In fact, amethyst was considered a cardinal gemstone until the 19th century, when a large source in Brazil made the gemstone more accessible.

It's important to remember that the term "precious gemstone" is subjective today and is used merely out of tradition. A precious gemstone can be less expensive and more plentiful than certain semi-precious gemstones.