Diamonds: Hardness vs Toughness

  1. If a diamond scratches glass, is it a real diamond?
  2. Can diamonds chip or break?

Diamond is one of the hardest natural substances known to man! But what does this mean? There is a scale called the Mohs scale of hardness, with Talc being #1 the softest and diamond being #10 the hardest.

What does hardness refer to? Hardness is defined as the resistance to scratching. Diamond being the hardest or tenth, making it extremely difficult to scratch.

As a matter of fact, the only thing that can scratch a diamond is another diamond. So…yes a diamond can scratch glass. But many things scratch glass. The ability of a gemstone to scratch glass is not an accurate test because glass is extremely soft and many stones scratch glass.

Diamonds do chip and can break! This is because diamonds are HARD (resistant to scratching), but they are brittle. If a diamond is hit in just the right direction and with enough force it may chip or break.

Let me explain further the difference between hardness and toughness (scratching and breaking). If I had a big piece of jade and a diamond in the palm of my hand, I could hammer a wooden peg into the ground with the jade without damaging the Jade (because it’s TOUGH). But if I tried the same with the diamond it would shatter (because it’s BRITTLE).


Jade is easily scratched by many things including diamonds. But diamonds are not easily scratched by jade or anything. I’ve seen diamonds after they were dropped in a garbage disposal! Always ask a professional appraiser if you have questions about diamonds.


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