What is the Mohs
scale?
The Mohs scale measures the hardness or durability of
minerals and natural gemstones. Hardness refers to the gemstone’s
ability to resist abrasion. In other words, it describes the
stone’s capacity to resist scratches from other minerals. If you
were to take a diamond (has the highest score) and try to scratch its surface
with a ruby (the next highest score), you would be unsuccessful.
However, if you were to take the diamond and scratch the surface of a ruby,
it would cause a scratch in the ruby stone.
The actual rating
Ten different
minerals or natural gemstones are graded on the Mohs
scale, from one to ten, with ten being the highest. The values,
however, are only used as a standard because the differences between a
natural gemstone that is ranked nine and one that is ranked ten is much
greater than one that is ranked eight versus nine. For instance,
a diamond (a rank of ten) is roughly four times as hard as corundum (a rank
of nine), while corundum is only twice as hard as topaz (a rank of
eight).
Listed below is
the Mohs scale of hardness for minerals and natural
gemstones:
 
Graphite
– 0.5
Talc
– 1
Gypsum – 2
Calcite – 3
Fluorite – 4
Apatite – 5
Feldspar – 6
Quartz – 7
Beryl (i.e. Emerald)
– 7.5
Topaz – 8
Corundum (i.e. ruby, sapphire) – 9
Diamond – 10
Mohs
scale relative to other objects
It’s
somewhat difficult to grasp the differences between the abstract numbers on
the Mohs scale. To put it into prospective,
the following items have the corresponding hardness:
Lead in a
pencil – 1
Fingernail – 2.5
Pearl - 2.5
Gold –
2.5 to 3
A penny – 3.5
Coral – 3
to 4
Platinum
– 4 to 4.5
Tooth - 5
The blade of a knife – 5.5
Opal –
5.5
Lapis – 5
to 6
Turquoise
– 5 to 6
Steel file – 6.5
Glass – 6
to 7
Garnet 7 to 7.5
Emerald –
7.5 to 8
COLOR GRADING
SCALE
A diamond works
like a prism, dividing light into a spectrum of colours. The colours reflect
in vivid flashes called "fire." Natural pigmentation in a diamond
acts like a filter and diminishes the fire. The less colour in a diamond, the
more varied the fire, and the better the colour grade.
Clarity
Diamonds that
are absolutely clear are the most sought-after and therefore the most
expensive. But virtually all diamonds have inclusions — scratches,
trace minerals or other tiny characteristics that can detract from the pure
beauty of the diamond, depending on how easily they can be detected.
All famous diamonds
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