Precious and semi-precious stones are used as gemstones, for jewelry, and for other adornments. They start as uncut, unpolished rocks, crystals, and minerals. Jewelers rely on their natural properties to determine how to refine them—by cutting facets or by tumbling rocks such as obsidian, agate, or jasper to polish them.
Anyone who has shopped for jewelry may have wondered about the differences between precious and semi-precious stones, which vary in beauty, rarity, and demand. The first thing to know is that some so-called “semi-precious” stones are actually more valuable than “precious” stones. These terms were first used in the 19th century and were largely based on the stone’s rarity. For example, purple amethysts were as valuable as rubies until a new source in Brazil was discovered in the 1800s. The gem’s rarity plummeted with the new supply, and amethysts were demoted from precious to semi-precious status.
Diamonds, emeralds, rubies, and sapphires are now generally considered the most precious stones in commercial jewelry. However, some stones classified as semi-precious are actually more valuable. Most people think that garnets are a deep burgundy color, but Tsavorite garnets are green, rivaling emeralds in beauty and value. They can be more expensive than a middling-quality sapphire.
Demand is another factor. Some extremely rare semi-precious stones are not broadly known, and their scarcity cannot support a market for them. Thus, lack of demand weighs more heavily than rarity in these stones’ value.
Precious and semi-precious stones are also assessed for their beauty using the four Cs—cut, color, clarity, and carats (size). Other factors matter as well, such as rarity, hardness, and durability.
Ultimately, the classification “precious” or “semi-precious” has less to do with value than with tradition. Natural pearls, opals, and jade are valuable, but they don’t earn the title “precious” by tradition in the commercial jewelry business.
Selecting a piece of jewelry comes down to taste and style. Consumers should do their research about prices to make sure a piece they like is fairly priced and to purchase something they think is beautiful.