Podcast 009: When do we call something a gemstone? In conversation with Henk Rijneveld FGA

The podcast is in Dutch, but available via YouTube with English subtitles, so you can listen in – even if your Dutch is not perfect. Below you will also find a summary text and resources for more in-depth reading.

In this episode of the Stack of Stones Community Podcast, Rolf Egberink talks with gemologist Henk Rijneveld FGA about the question: When do we actually speak of a gemstone? We dive into the different definitions from mineralogy and gemmology and discuss why there is so much confusion about this.

Is it always a mineral? What do we do with rocks, fossils, pearls or even synthetic material? And what about the term “semiprecious stone”? We bring in nuances, compare historical and modern understandings, and explore the impact of these definitions on collectors, sellers and lovers of gems and minerals.

Don’t miss this fascinating episode and gain a better understanding of the different views within the world of minerals and gemstones!

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Summary podcast and resources

Historical background of the term ‘gemstone’

• Antiquity: Already in classical antiquity, a distinction was made between “common” stones and precious stones.
• Pliny the Elder (1st century AD): Described stones and marbles in Book 36 of the Naturalis Historia and gems, including amber and pearls, in Book 37. You can find an English translation of the Naturalis Historia here.
• 18^th and 19^th centuries: Mineralogy and gemmology diverge in definitions. Mineralogists focused on chemical and physical properties, while gemmologists were concerned with aesthetics and use in jewelry.
• Now: No single definition used by all disciplines.

What do mineralogy and gemmology say about the definition of a gemstone?

• Mineralogy: Strict definition, where a gemstone must be a mineral and have some special properties such as hardness (>7/8 Mohs), rarity and beauty. Related to the definition of a mineral, organic materials such as amber and pearls, rocks such as lapis lazuli, and man-made stones are not included.
  • Simplified definition of a mineral (Nickel, 1995): A mineral is an element or chemical compound that is normally crystalline and formed as a result of geological processes.
• Gemmology: Broader definition, in which not only minerals but also organic materials such as amber, coral and pearls are considered gemstones, as are natural stones that are beautiful enough to be worked and incorporated into jewelry, such as lapis lazuli or obsidian. Do we consider the stone a gemstone? Then it is! Hardness (durability), rarity and cultural use certainly play a role.
  • Definition CIBJO: Natural inorganic, organic or biogenic material formed entirely by nature without human intervention. Gemstones are usually used in jewelry or artifacts because of a combination of properties that give them beauty, rarity and relative durability.

Sources for more background information:

• List of official registered minerals on the International Mineralogical Association (IMA) website
• Historical book: e.g.“Taschenbuch der Edelsteinkunde fur Mineralogen” (1834), amber and natural (volcanic) glass classified as gemstones, you can find a pdf of this book here
• CIBJO The Gemstone Book and other BlueBooks (diamonds, pearls, etc.).

‘Semi-precious stones’ and ‘ornamental stones’

• The term semi-precious stone was historically used to distinguish softer and less rare gemstones from the Big Four (diamond, ruby, sapphire, emerald). No clear limits to the definition, mainly based on commercial incentives.
• Since 1967, the term semiprecious stone has been officially abandoned, but is still used in commerce and in popular books and websites. Sometimes the term “ornamental stone” is used in its place, but even of this the definition is not clear.
• Avoid use of the terms “semi-precious stone” and “ornamental stone,” remain: gems and stones. Name primarily what the material is, where the scientific name and/or trade name can be used. The explosion of fancy names and trade names unfortunately create additional confusion.

Sources for more background information:

• Historical source on Big 4/5:“A Book of Precious Stones” (1909), p. 9, a pdf of the book can be found here
• Overview of commercial and scientific designations in the Gem or Scam Library

Artificial materials, gemstone or not?

• Synthetic “gemstones”: Materials such as synthetic ruby or spinel, which are chemically identical to natural varieties. Due to creation via human intervention not a mineral and thus actually not a gemstone.
• Artificial products: Man-made stones with no natural counterpart, for example, Swedish Blue (slag glass) or glacierite (industrial byproduct). Are offered as gemstones but are not actually so, rather an artificial stone with its own identity.

Sources for more background information:

• Article on glacierite, an artificial product, on Henk Rijneveld’s website

Rocks, gemstone or not?

• Materials such as lapis lazuli and kiwi jasper are sold commercially as gemstones, but are technically rocks and not minerals. While lapis lazuli has historically been considered a gemstone, of kiwi jasper (a granite) this is questionable.
• Historical meaning of “jasper“: The name has historically been used for a variety of opaque, mottled stones in which the naming is not so closely observed today.
• Even with “granite” or other rocks, aspects such as beauty and quality of processing affect whether you would call it a gemstone.

Sources for more background information:

• Podcast episode about jasper

Practical implications for collectors and sellers

• Discussion about the definition of what we mean by a gemstone has been going on for a long time and will continue. Nuances in the discussion are desirable, and mineralogy and gemology can be complementary to each other.
• Above all, name the material (stone) appropriately, where the scientific name and/or trade name can be used, and be transparent about origin and treatment. Use the existing guidelines of IMA and CIBJO.
• Think logically and be critical of what is sold as a gemstone. Would the material be used for a piece of jewelry or decorative item?
• Gemstones should be “tactile”. While scientific definitions are important, aesthetics and emotional value also play a role in how we value gemstones.

Do you have any questions or comments? Post them below this post or in the Stack of Stones community!

Also read more stories about gemstones by Henk Rijneveld FGA on his website.