KNOOP Hardness	in kg/m2
Diamond	8800
Cubic Boron Nitride	4500
Boron Carbide	3000
Silicon Carbide	3000
Titanium Carbide	2400
Tungsten Carbide	2200
Aluminum Oxide (Aluminum, Corundum, Ruby)	2000
Quartz	820
Glass	530
Steel	200 - 1000

Besides having the supreme hardness, the synthetic diamond also has the highest compressive strength, the highest heat conductivity and exceptional optical transmission. And it is an excellent electrical insulator, its corrosion resistance is also very high.

Thermal Conductivity in	W/(m*°K)
Diamond	600 - 2100
Copper	400
Aluminum	200
Tungsten Carbide	100
Graphite	65
Nickel	60
Silicon Carbide	10 - 100
Aluminum Oxide	9 - 25
Granite	2 - 5

Main characteristics playing an important role in the mechanical performance of diamond grits at work are:

•  accurate size average in microns and stones per carat (on electroformed sieves)

•  standard deviation of said size measurement

•  average shape factor in 3-D

•  standard deviation of said shape measurement

•  toughness index (half life on friability test)

•  micro-chipping resistance

•  fatigue resistance (simulating impact energy of real life in a sawing process)

•  pure wear resistance

•  thermal toughness resistance

•  micro-chipping resistance after heat treatment

•  thermal stability

The combination of these 13 characteristics gives a good idea of the performance index.

Some more measurements have an analytical purpose:

•  single crystal test (giving the spread of the compressive strengths grit by grit)

•  image analysis by computer for shape factor in 2-D, e.g. eccentricity

•  scanning electron microscope for deep investigation

•  purity measurement, in relation with thermal stability

•  color values, useful for simple reliability assessment

All measurements are performed in CUSTODIAM laboratory