What is the Difference Between a Precious and Semi-Precious Stone?

For centuries now, jewelers have used the categories “precious” and “semiprecious” to describe the supposed value and rarity of certain gemstones. But do these designations have any real meaning? What do we mean when we call a gemstone precious?

As the Gemological Institute of America (GIA) points out, referring to precious gemstones and semi-precious gemstones is misleading as it implies that precious gemstones possess greater value than their semi-precious counterparts.

Take a diamond: it has long been considered a precious gemstone—maybe the precious gemstone. Professional gemologists, however, know that the value of a diamond has little to do with its “preciousness.” Diamonds are valuable because they are rare. 

How rare are diamonds though? How difficult is it to mine diamonds compared to other gemstones? A diamond, as it turns out, is not nearly as rare as a Brazilian paraiba tourmaline, an absolutely exquisite gem whose color ranges from a brilliant turquoise to a majestic cyan. 

To put the rarity of paraiba tourmaline into perspective, there is roughly one paraiba tourmaline, a “semi-precious” gemstone, mined for every 10,000 diamonds. 

Photographed from the GIA Collection for the CIBJO project from the Dr. Eduard J. Gubelin Collection. Collection# 33379, 2.59 ct turquoise blue triangle cut Paraíba tourmaline; Collection# 33382, 3.28 ct electric blue drop cut Paraíba tourmaline; and Collection# 33378, 3.68 ct green pear cut Paraíba tourmaline.
Photographed from the GIA Collection for the CIBJO project from the Dr. Eduard J. Gubelin Collection.
2.59 ct turquoise blue triangle cut Paraíba tourmaline, 3.28 ct electric blue drop cut Paraíba tourmaline and 3.68 ct green pear cut Paraíba tourmaline.

Paraiba tourmaline’s value can also be expressed thusly: a three-carat Brazilian version of this gemstone is unheard of, yet you can easily find a three-carat diamond to buy nearly anywhere today.

The cost of paraiba tourmalines, especially in their vivid “windex” blue or “neon” blue-green varieties, far exceed that of a diamond. And for good reason! It is a rarer stone, far more coveted by the majority of gem connoisseurs the world over.

The fact that paraiba tourmalines are considered semi-precious gemstones gives us a good indication of just how meaningless the categories of precious and semi-precious are.

Paraiba tourmaline and gold custom ring
Custom Paraiba Tourmaline Engagement Ring

The Garnet: A Precious Gemstone?

There are many gemstones that are rarer than diamonds, and their color plays a key role in determining their value.

Are emeralds precious or semi-precious gemstones? Are rubies precious or semi-precious gemstones? Are garnets precious or semi-precious gemstones?

Only four gemstones—emeralds, rubies, sapphires, and diamonds—are classified as precious stones. But this has more to do with advertising and outdated tradition, and much less to do with the rarity, brilliance, and value of these particular stones.

For instance, the correct answer to the question about garnets would be: it depends. What do we mean by precious?

Taking the garnet as an example elucidates the distinction between precious and semi-precious in gemology. For, when it comes to garnets, these outmoded categories simply do not represent modern values: while red garnets are relatively inexpensive, a green garnet tsavorite or a demantoid garnet are far more valuable, expensive, and precious than an emerald.

Photographed from the GIA Collection for the CIBJO project.
Top row, left to right: 16.94 ct yellow oval garnet, 19.89 ct round orange spessartite garnet, 44.28 ct round, deep pink rhodolite garnet, 16.99 ct reddish orange cushion cut garnet and 7.26 ct cushion cut tsavorite garnet.
Bottom row, left to right: 8.20 ct oval greenish yellow garnet, 12.36 ct oval golden yellow garnet, 9.22 ct pink pear cut garnet, 14.53 ct light green cushion cut grossular garnet and 4.32 ct bluish green cushion cut garnet.

As one of the rarest varieties of garnet, demantoid green garnets can possess a brilliance and fire that greatly exceeds emeralds and diamonds. 

Interestingly, the difference between tsavorite garnets and demantoid garnets is subtle, but important: while the green hue of these two distinct varieties of garnet can overlap, the tsavorite is green grossular, while the demantoid is green andradite.  

Andradite is softer than grossular on the moh scale, but possesses greater refraction and color dispersion.

Importantly, however, green garnets are much more precious—if by precious we mean rare and valuable—than rubies, emeralds, diamonds, or sapphires.

Color and the Value of Gemstones

Rather than throwing around meaningless terms such as precious and semi-precious, we should evaluate gemstones based on the following criteria:

  • How rare is the stone?
  • What is its cut?
  • What is its color?

The value of colored stones is determined by their saturation and evenness of their color. In addition, many rare colored gems present atypical variants of more common stones (i.e. the exclusive green garnet) related to their chemical properties, which is, in turn, a product of their geographic area. 

For instance, when we referenced the Brazilian paraiba tourmaline above, we were referring not merely where the gem was mined, but the geology of the region that produces this gem in an electric hue.

How stones are cut and set matters a great deal as well because it can enhance a gem’s natural beauty.

True  gemstone jewelry designers know that the distinction of precious and semi-precious have little to no meaning. At llyn strong, we will discuss the rarity, the color—as the color pertains to the rarity—and the cut of the gemstones in our handcrafted pieces, but we avoid categorizing stones as precious and semi-precious for all the reasons we’ve offered above.

Why, after all, continue to uphold inconsequential definitions?

gemstone event_gemstone roundtable_jewelry event_jewelry store greenville sc
Various Gemstones at a Gemstone Roundtable

Learn more about gemstones at a Gemstone Roundtable, hosted in-house at llyn strong fine art jewelry each year in the Fall and Spring. You can also browse our Virtual Gemstone Roundtable with videos of various available gems where our Graduate Gemologist (the Doc of Rocks), Sydney Strong talks about each stone.

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