Dec 312011

Diamond cut is one of the 4C’s: Cut, Clarity, Color, Carat Weight.

When most people think of diamond cut, they think of shape like round, princess, marquise etc.
At first glance that seems to make sense, but it is not correct.

Diamond cut actually refers to how the facets and angles are put on a diamond. The cut is considered by many as the most important of the 4C’s and has a major impact on the brilliance, fire and overall appearance of the diamond.

Of course what looks best is subjective and there has never (until recently) been a standard
that has been accepted within the industry.

In 1919 a mathematician by the name of Marcel Tolkowsky came up with his idea of what
proportions a diamond should have in order to produce a beautiful diamond. The idea
of cut is to get as much light to enter the diamond, bounce around inside and be returned
back out the top to the viewers eyes. The more light that you can return to the viewer (without leaking out the sides) the more impressive the diamond.

Diamonds being cut within Tolkowky’s ideal range may look nice, but for some reason the industry did not widely accept the range as a standard.

The GIA which is recognized as one of the leaders in diamond grading, research and education
embarked on the massive task of coming up with a cut grade system. Obviously their desire
would be to get their system accepted by the industry.

They spent more than 10 years researching diamond cut, finally updating their reports with the addition of a cut grade (for round diamonds only) in 2006. They do not use the term ideal cut, rather they released a fairly simple scale which goes from Excellent to Poor.

  • Excellent
  • Very Good
  • Good
  • Fair
  • Poor

Their cut grade was immediately accepted by the industry, they license the technology to

other diamond labs and hardware manufactures such as Sarin and OGI Systems.

Prior to the GIA’s standard diamond cutters would essentially cut a diamond as they
wished, often to retain as much weight of the rough diamond as they could rather than
cut the diamond to make it perform as well as it could. Diamonds are sold by weight
so it was to their advantage to keep as much of the weight as possible.

The GIA cut grade system makes it easy to pick a diamond based on the cut grade which is clearly stated on the diamond report. The difference in appearance between a diamond that has the grade excellent vs. good can be quite amazing.

As a general rule of thumb, if you are buying a round diamond you want to purchase the
highest cut grade you can afford. The price difference between a poor cut and excellent
cut diamond is massive and so is the visual appearance.

The good news is there are very few diamonds entering the market that are have cut grades below Very Good.  Diamond buyers made their choices known, they want a quality cut diamond and diamond cutters now cut largely based on the GIA cut grade scale.