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How to Test the Hardness of a Diamond

Various scales can measure the hardness of a diamond. A diamond is rated for hardness based on the types of materials that can scratch it. By applying force to the diamonds, gemologists and hobbyists can measure how hard their diamonds are. The industry standard for executing these tests is the Rockwell tester, which will make two indentations on your diamond and measure them against each other to determine the diamond's hardness.

Things You'll Need

Rockwell tester
Gemology ruler

Instructions

- 1
  Put the diamond onto the Rockwell tester.
- 2
  Apply one minor load by pushing the minor load button on the Rockwell. The minor load is 10 kilograms, which comes from a small steel ball or a diamond cone. This ball or cone makes an impression on the diamond. The impression will be the seat for your major load.
- 3
  Lift the minor load with the knob on the Rockwell. Apply one major load, which is a 100-kilogram load. This uses the same steel ball or a diamond-tipped ball, which can give you a 150-kilogram load.
- 4
  Measure with a gemology ruler the difference in the indentations of the minor and major loads. Note that difference and line it up with the Rockwell hardness scale.

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