Ask A Scientist Environmental Earth Science Archive

name         Jerolyn W.
status       educator
age          40s

Question -   Is there anything that can scratch a diamond?  Will another diamond scratch 
it? 
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A diamond has a hardness of 10 on a scale of 10 known as Mohs Hardness Scale.  A diamond can 
scratch any other mineral and only a diamond can scratch a diamond.

An old myth/legend to test for a diamond was to see if the mineral would scratch glass and 
if it did, it was a diamond.  Actually there are many other minerals that will scratch glass 
including quartz (very common), corundum (gem forms are called sapphire and ruby), garnet, 
topaz, and others.

Steven Miller
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Generally, another diamond will scratch it.  I do not recommend scratching
jewel grade or cut diamonds on anything (like a mirror) or with another
diamond.  There may be planes of weakness in the natural crystal structure
and the diamond can split.

Pat Rowe
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Diamonds will scratch diamonds, with difficulty. However, just recently
synthetic "diamonds" have been made that are harder than "natural" diamonds.
This is very recent so a Google search should snag a reference easily.

Vince Calder
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