The classification of gemstones as "precious" or "semi-precious" is used to distinguish between rare, valuable stones and more readily available ones. In the past, diamonds, emeralds, rubies, and sapphires were considered precious, while all other gemstones fell into the semi-precious category.
However, the distinction between precious and semi-precious gemstones is not as widely used or strictly followed. The value of a gemstone is now determined based on factors such as its rarity, quality, and demand rather than its classification as precious or semi-precious.