Moh's Scale
MOH'S SCALE - DETERMINING GEMSTONE HARDNESS
If you are interested in gemstones or minerals, you have likely heard the term Moh's scale. But exactly what does this scale tell us about metal hardness?
Mohs Scale
This term refers to a scale of relative hardness
of various minerals which was developed by the German mineralogist Frederich
Mohs in 1812. It is now routinely used by modern jewelers and gemologists to
differentiate between various gemstones. So, if you are shopping for gemstone
jewelry, it's a good idea to have some understanding of the Mohs scale.
Classifications
The scale consists of 10 classifications with the
softest being #1 and the hardest being #10. Talc is considered the softest
and diamonds the hardest. Mohs based his scale on 10 minerals that were all
readily available. The scale tells you how easily a mineral or gemstone can
be scratched by others. Therefore, according to this scale, the diamond can
scratch all others minerals, but cannot be scratched by any of them so it is
the hardest on the Mohs scale.)
How does it work?
The Mohs scale is actually very low tech. Basically
jewelers and gemologists test their unknown mineral against one of these standard
minerals. Whichever one scratches the other is harder, and if both scratch
each other they are both the same hardness. It's that simple. However, sometimes
a mineral will fall in between the numbers of 1-10 so you might find one rated
2 1/2-3, for instance. To give you an idea in layman's terms - your fingernail
is a #2, a copper penny is #3, and glass is approximately #6-7.
The Mohs Scale of Hardness
Here is a table of the Mohs scale showing the relative
hardness of the common minerals used in it. Photos are credit of widipedia.org.
Hardness |
Mineral |
Description |
Examples Relating to Jewelry |
| 1 |
Talc |
Can be scratched with a fingernail and by any stone rated 2+. |
|
| 2 |
Gypsum |
Can be scratched with a fingernail and any stone rated 3+. |
Amber, Ivory, Shell, Jet, Silver, Gold, Copper |
| 3 |
Calcite |
Can be scratched with a knife and any stone rated 4+. |
Bronze, Coral, Pearl, Azurite, Platinum |
| 4 |
Flourite |
Can be scratched with a knife and any stone rated 5+. Will scratch any stone rated 3-. |
Iron |
| 5 |
Apatite |
Can be scratched with a knife and any stone rated 6+. Will scratch any stone rated 4-. |
Lapiz Lazuli |
| 6 |
Orthoclase |
Can be scratched with a knife and any stone rated 7+. Will scratch any stone rated 5-. |
Opal, Peridot, Moonstone, Garnet, Jade, Rhodium |
| 7 |
Quartz |
Will scratch glass and any stone rated 6-. Can be scratched by stones 8+. |
Amethyst, Chalcedony, Aquamarine, Emerald |
| 8 |
Topaz |
Will scratch glass and any stone rated 7-. Can be scratched by stones 9-10. |
Spinel, Tourmaline, Zircon, Chrysoberyl, Chromium |
| 9 |
Corundum |
Will scratch glass and any stone rated 8-. Can be scratched by diamond. |
Ruby, Sapphire |
| 10 |
Diamond |
Will scratch glass and all stones 1-9. |
Diamond is the hardest of all minerals and 4 times harder then Corundum. |
Why is this scale important to you as a lover of jewelry?
Hardness is a particularly important quality for
gemstones. Most soft minerals are not cut as gems. Most gemstones used in jewelry
have a hardness of 7 or more. So, if you know that your gemstone has a lower
hardness than this, you will also know that it may quite easily scratch when
worn.
I try to offer accurate vintage jewelry information, but may make errors from time to time due to mistakes in research information.
