Poor cut

Poor Cut Grades
Poor Cut Diamonds don't sparkle much. The Angles and Proportions and Symmetry may be all over the place.
The Depth could be very Deep or very Lumpy. A Cut like this could also be very Thin and Vulnerable to Chipping or Cracking.

Poor Cut: A poorly cut diamond can be either cut too deeply or too shallow. A deep or shallow cut diamond will lose or leak light through the side or bottom. This results in less brilliance and value.

Poor Cut:
Poorly cut diamonds with proportions and finish that make them look relatively lifeless to the eye. We do not recommend such stones for fine jewelry.

Poor Cut: Any diamond that is cut in such a way that it loses most of the light that tries to pass through the stone. It will generally not be dispersed out of the diamond.

Poor Cut
Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. A poorly cut diamond can be cut too deep or too shallow.

Avoid Poor cut diamonds, even if size is the primary concern. Most find these diamonds to be an unacceptable trade off, despite the lower price. Lumera does not offer Poor cut diamonds.

Poor - Poor cut diamonds are typically cut too shallow or too deep causing much of the light to leak out of the diamond's sides and base. Most high end diamond retailers do not carry Poor cut diamonds.
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Fair & Poor Cut Diamonds
A diamond graded as fair or poor cut reflects only a small proportion of the light that enters it. Typically these diamonds have been cut to maximize the carat weight over most other considerations.

Fair and Poor Cut - A diamond in this grade reflects only a small proportion of the light that enters it. These gems are created to maximize carat weight over other considerations.

There is no way a high color or clarity grade can offset the visual results caused by poor cutting. But a well cut diamond with less than average clarity and color can be a dazzling spectacle of light and fire.

Commercial grade ("Thai" or Mong Hsu; poorer color, +inclusions, poor cut) stones of the same size was selling for about $100-1000/ct (wholesale) in 1990, as it is today.
Fine gemstones of documented Burmese (Mogok only) origin sell for a premium.

These are Ideal, Premium, Very Good, Good and Fair & Poor cut. In ideal and premium cuts, light is reflected brilliantly creating the sparkle in the stone. Ideal cut is valued most while fair & poor cut is least.

However, the variance in the proportions between an Ideal Cut and a Poor Cut can be difficult to discern by the casual observer.

fish-eye A dark gray to black (achroic) spot at the center of the gem caused by improper proportions from poor cutting; see also extinction.
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Fair Cut: Being not as brilliant as a Good cut, Fair cut grade quality diamonds refract less amount of light, but make a better choice than Poor cut diamonds.
Diamond Dimensions
The various dimensions of a diamond are defined as follows: ...

An Ideal, Very Good, or Good make will have proportions that maximize the brilliance and fire of a diamond. A poor cut will result in a diamond that has little sparkle and cannot properly reflect light because of the way it was cut.

that there are optimal proportions in the shape of a diamond, and diamonds are graded by cut from Ideal to Poor. The cut is what determines the brilliance of a particular stone. Generally, even the difference between an ideal cut and a poor cut is ...

Ideal or Excellent cuts release the inner brilliance of the stone and project maximum amount of fire and sparkle where as Very Good, Good and Fair cuts loose some light that enters the diamond. A poor cut looses most of its light from the diamond ...

Many gemologists believe this is the most important - though most misunderstood - of The Four "C"s that determine a diamond's quality and value. Even if a diamond has perfect color and clarity, a poor cut will cause it to lose sparkle.

Fair Cut: While still capturing some sparkle, this cut is lacking in brilliance when compared to the Good and Very Good cuts.
Poor Cut: A clearly dull and lifeless diamond that sacrifices proportion and quality.

is what jewelers refer to as brilliance- the unique light show produced by a fine diamond. Most gemologists consider cut the most important diamond characteristic because even if a diamond has perfect color and clarity, a diamond with a poor cut will ...

See also: Cut, Diamond, Stone, Jewel, Color