EDUCATION

DIAMOND CUT
Overview
Inferior Cut
Diamond Proportions
Polish & Symmetry

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about Diamond Cut

Excellent Cut Round Diamond

When it comes to the four Cs of diamond buying (cut, color, clarity, and carat), most people seem to feel that size is the most important aspect of the selection process. However, it is the cut of the diamond that can have an effect on each of the other points of consideration. For example, a large table (the flat surface on top of the stone) can showcase even the most minute inclusions. And that’s just one way the cut is important to the overall quality of the stone. So before you settle on a diamond, think about how different cuts can affect the overall purchase.

The first thing to know is that there are various facets of a stone that will differ from cut to cut. The portions of a diamond that are important are the table, the crown (the height of the top portion of the diamond), and the pavilion (the depth of the bottom portion of the stone). The girdle (where the crown and pavilion meet) and the culet (the small surface on the very bottom of the stone) also play a role in both the brilliance and overall quality of the stone, but they’re not as important (unless they are badly bungled). The exact measurements of these portions of the stone are going to determine whether or not it sparkles, displays flaws, exhibits color, and so on, so you need to consider which cuts emphasize different traits.

An emerald-cut diamond, for example, tends to have the largest table, meaning it requires an exceptionally flawless stone to pull off. The same goes for an asscher cut. If the clarity or color is off, it will be more pronounced in these cuts. Round cuts, on the other hand, tend to exhibit the most brilliance, but this can be reduced if the stone is cut too shallow (as in, a small pavilion depth). Pear- and heart-shaped diamonds, while unique, may reflect light strangely because they are not entirely symmetrical. And cushion, oval, and marquise cuts simply aren’t very deep, but they tend to be less expensive because they contain fewer carats.

So regardless of the cut you choose, it will have an impact on the beauty of your stone. That doesn’t necessarily mean you should discount certain cuts because of the potential for problems, it just signifies a need to take care when choosing the cut of your stone. Just be sure to look for any flaws that may be more apparent due to a particular shape.

DIAMOND CUTTERS

A diamond cutter spends years mastering his craft, learning how best to cut a rough diamond to achieve the ultimate cut with the fewest imperfections and the least loss of carat weight. The better the cut, the more valuable the diamond.

Over 500 years of diamond cutting expertise have evolved into the modern-day brilliant diamond cut you see today.
A diamond's cut is considered to be the most important of the four Cs. It is important to understand how a diamond's proportions and the relationship between them affects its brilliance, fire, and scintillation.

Most diamonds are "spread" in their cutting to retain maximum weight from the original rough diamond. This technique results in a heavier diamond and also sacrifices the potential fire and brilliance of the stone. The width and depth have the greatest effect on how light travels within the diamond, and also how light exits the diamond in the form of brilliance.

Shallow Cut Diamonds
When a diamond is cut too shallow, light leaks out of the bottom, brilliance is lost and the diamond appears watery, glassy and dark.
A diamond with these characteristics is referred to as a "fisheye".

Deep Cut Diamonds
When a diamond is cut too deep, light leaks out of the sides,
brilliance is lost and the center of the diamond will appear to be dark.
A diamond with these characteristics is referred to as a "nailhead".
A diamond's cut is graded by several measurements. Its depth percentage (a measurement of the height vs. the width of the stone) and its table percentage (a measurement of the diameter of the top facet of the stone vs. the stone's average width) are two key factors in determining the quality of a diamond's cut. These percentages are detailed on the GIA or AGSL Diamond Grading Report that accompanies every Adiamor loose diamond.

Experts express differing opinions on the best table size (the diameter of the largest facet on the top of the stone) and the best depth for a diamond, because these two factors alone are not sufficient enough to accurately judge a diamond's cut. Other factors such as crown angle, girdle thickness, culet size, polish and symmetry all play a role in judging a diamond's overall cut quality.
Although polish and symmetry are graded under 10X magnification they can both have an effect on the overall appearance of a diamond. Polish refers to the quality of the diamond's surface and includes such features as nicks, polish lines and abrasions. Symmetry refers to the exactitude of the shape and alignment of the facets.

Off-center culet
Facets not properly pointed

Misshapen facets
Crown and pavilion misalignment

Off-center table
Table and girdle not parallel
- The polish and symmetry grades are listed on each diamond's detail page and within their accompanying GIA or AGSL diamond grading report.
- GIA grades polish and symmetry as:
  
  Excellent (EX)
  Very Good (VG)
  Good (G)
- AGSL grades polish and symmetry as:
  
  Ideal (ID)
  Excellent (EX)
  Very Good (VG)
  Good (G)
- Adiamor does not carry diamonds with polish and symmetry grades of:
  
  Fair (F)
  Poor (P)

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