Used to Measure CZ Hardness, What Is the Mohs Scale?
The hardness of loose cubic zirconia, lab created gems and naturally formed gemstones is measured by the Mohs scale. For instance, natural diamonds, Earth’s hardest mineral, are a perfect 10 on the Mohs scale. Lab created cubic zirconia are nearly as hard, registering 8.5 Mohs. Common talc (as in talcum powder) which can be easily scratched with a fingernail is the least hard mineral, rating a lowly 1 on the Mohs scale.
A useful scale universally used to grade the hardness of minerals, the Mohs scale was developed nearly 200 years ago by German mineralogist and geologist Carl Friedrich Christian Mohs (1773-1839). After studying at the famous Mining Academy of Freiberg in Saxony, followed by a stint as a pit foreman at the Neudorf/Harz mine, Mohs was hired by wealthy banker J.F. van der Null to classify and organize his extensive mineral collection.
At that time, mineralogists classified minerals by their chemical composition. Mohs departed from the norm by choosing to classify van der Null’s collection by the physical properties of the minerals. He differentiated the various minerals by crystal morphology, cleavage, density and hardness. In the process, Mohs developed methods of easily — and inexpensively — determining one mineral from another by observation and simple tests that could be conducted in the field. Mohs published his innovative methodology in 1812 while serving as Professor of Mineralogy at the Joanneum in Graz, Austria.
Mohs’ mineral identification methods revolutionized mineral collection and became the universally recognized standard for mineral identification still used by wholesale jewelers and mineralogists today. In fact, while cubic zirconia gems look just like their natural diamond counterparts, jewelers use weight as a quick and easy method to distinguish the two. A loose cubic zirconia gem weighs about 1.5 times as much as a diamond of the same size.