Gemstone Hardness Verses Toughness

Photo: Effy necklace, bracelet, and earrings from Macy's and the ring from Istdibs

When jewelry lovers select gemstones for everyday wear they usually think of diamonds for their hardness, but hardness is only half of the gemstone durability story.

Gemstone durability is a combination of hardness and toughness. Hardness refers to the surface strength of a stone to resist scratching. Harder stones can scratch softer stones. A diamond can scratch a sapphire, ruby, emerald, topaz, and on down the line of Moh's Hardness Scale. Only another diamond can scratch a diamond.

Sotheby's

But while hard, a diamond isn't tough, it's brittle and will chip, crack, or shatter if abused. It's why you should remove your rings while working with your hands. Although diamonds, a 10 on Moh's Hardness Scale is 4 times harder than sapphires, a 9, sapphires are tougher than diamonds, and it takes a greater force to shatter them.

Toughness refers to the inner strength of a gemstone to resist breakage under force or stress. A diamond is brittle due to its perfect cleavage, which is an atomic structure that runs parallel making the bonds between its planes weaker than gemstones with less parallel, or imperfect cleavage. Certain softer gemstones are tougher than diamonds, meaning less brittle and more difficult to break apart with blows or force.

So what's the toughest gemstone? There are picture clues.😏 It's jade. Geologists have a saying, " Jade (rating  6 - 7 in hardness) can't scratch a diamond, but jade can break a diamond."

WEJ

Jade is the national gemstone of Japan and is popular in many Asian cultures. For over 5,000 years jade has been fashioned into tools, sculptures, and jewelry. Originally jade was thought to be one mineral but in 1863, Frenchman Alexis Damour established that jade was in fact, 2 minerals, either jadeite (Na(Al, Fe3+)Si2O6) or nephrite (Ca₂(MgFe₅Si₈O₂₂(OH)₂). Jadeite is an aluminum-rich pyroxene while nephrite is a magnesium-rich amphibole. To the human eye, however, they are difficult (though not impossible for an expert) to tell apart.

Jadeite (at 6.5 - 7) is slightly harder than nephrite (at 6 - 6.5) and is in greater demand in Asian countries. Not only is Jadeite jade harder, but denser and easier to work with and polish into a shine. Sometimes jewelers dye jade but over time the dye can fade.

Photo: Sotheby's

Burma (now called Myanmar) produces jadeite, the most sought-after type of jade in Asian countries. Jadeite's most valued color is emerald green, but other colors include black, white, red, yellow, blue, purple, pink, grey, brown, and orange. The finest quality jadeite jade is pure green with high transparency and shine called imperial jade. Other prized jade is kingfisher jade — only slightly less intense than imperial jade; apple jade — a vivid yellow-green; and moss-in-snow jade — "translucent white with bright green veining, patches, or spots," according to The Gemological Institute of America (GIA).

Stronger than pearls and diamonds, jade is toughhh... pretty... and much of it affordable. Especially wearable on Christmas, St. Patrick's Day, and in the spring! Alas, I don't own jade. How about you?

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