Semi-precious is an old trade label for every gemstone outside the traditional precious group of diamond, ruby, sapphire and emerald. This section covers those other gems: agate, jade, lapis lazuli, moonstone, turquoise and dozens more. Many are affordable and widely available, while some are scarce and costly, which is exactly why the label causes trouble.
Where the split came from
The two-tier idea took hold in European jewelry during the 18th and 19th centuries. Diamond, ruby, sapphire and emerald were hard, intensely colored, linked with royalty and imported in small amounts from distant mines. Other gems, many of them mined closer to home or found in large pieces, were grouped below them. Bohemian garnets and agates cut in Idar-Oberstein were sold widely at modest prices in the 19th century.
Before that, the line was blurry. Ancient and medieval jewelers prized lapis lazuli, carnelian and turquoise as highly as any stone. Amethyst was valued like ruby and sapphire until large Brazilian deposits appeared in the 19th century.
Why the term is a problem
The label suggests that a whole species is second rate, and that does not hold up. Fine imperial jadeite can be among the most expensive gem materials sold at auction. A top tsavorite garnet or fine black opal can cost more per carat than an average sapphire. Meanwhile, plenty of low-grade ruby and emerald sells for very little. Price depends on the individual stone, not its category.
The word also has no scientific or legal definition. The U.S. Federal Trade Commission's Jewelry Guides use "precious" and "semi-precious" mainly in one context: they say it is deceptive to apply either word to a stone that is synthetic, imitation or otherwise made artificially. Many gemologists and gem dealers avoid "semi-precious" altogether and simply call these stones gems or colored gemstones. This site keeps the section name because readers still search for it, but each profile judges its gem on its own merits.
Gem families in this section
Most of the stones here belong to a few mineral groups. Knowing the family explains a lot about a gem's hardness, look and care.
Quartz and chalcedony
Quartz is silicon dioxide, about 7 on the Mohs scale, and comes in two forms. Crystalline quartz forms visible crystals and gives faceted gems such as amethyst and citrine, plus included varieties like rutilated quartz and tiger's eye. Chalcedony is made of microscopic quartz crystals packed together. It includes agate, carnelian, onyx, chrysoprase and jasper. Because chalcedony is slightly porous, it takes dye easily, and much colored agate and black onyx on the market has been dyed.
Feldspar
The feldspar group is the most common mineral group in the Earth's crust, and a few members make fine gems. Moonstone shows a soft floating glow called adularescence. Labradorite flashes blue, green and gold. Sunstone sparkles with tiny reflective platelets. Feldspars sit around 6 to 6.5 in hardness and have cleavage, so they need some care in rings.
Other species
The rest of the section covers single species and rocks with their own character:
- Jade, the name for two different minerals, jadeite and nephrite, both prized for their toughness.
- Turquoise, a copper phosphate often stabilized to improve durability.
- Lapis lazuli, a rock of lazurite, calcite and pyrite.
- Spodumene (kunzite), beryl varieties like morganite, chrysoberyl, diopside, kyanite, apatite and titanite.
- Malachite, prehnite and other opaque or translucent stones used for cabochons and carving.
How to use these profiles
Each profile opens with a quick facts box and covers color, sources, treatments, imitations and care. The gemstone durability guide compares wearability across species. For the classic big four and other major jewelry gems, see the precious gemstones section.
Frequently asked questions
What is the difference between precious and semi-precious stones?
Historically, precious meant diamond, ruby, sapphire and emerald, and semi-precious meant everything else. The split has no scientific basis and does not reliably predict value.
Is the term semi-precious still used?
Yes, by many retailers and shoppers. Many gemologists avoid it, and the FTC Jewelry Guides say it should never be used for lab-made or imitation stones.