Deep cut

Deep Cut: Deep Cut will allow light to be lost through a diamond's sides causing it to appear dark.

Ideal Cut: Ideal Cut is considered as the best cut and it will reflect most or all of the light that enters in the diamond back to the eyes.

Deep Cut: When a diamond is cut too deep, it will lose or leak light through the side or bottom. This results in less brilliance and value.

Deep Cut
In which light refracts away through the sides.
GIA Cut Grading ...

Deep Cut Diamonds
When the cut of a diamond is too deep, some light escapes through the opposite side of the pavilion.

Deep cut
Cut refers to the angles and proportions a skilled craftsman creates in transforming a rough diamond into a finished diamond. When a diamond is cut too deep, it will lose or leak light through the side or bottom.

A too-deep cut diamond (orange) would yield a significantly larger diamond, earning the diamond cutter a larger profit on his investment.

A deep cut in colored stones is aimed to darken the color. However to achieve a deep cut one has to sacrifice weight. Such type of stone is suitable for being mounted on jewelry.

The "Shallow Cut" and "Deep Cut" examples in Fig. 1 show how light that enters through the table of a Modern Round Brilliant diamond reaches the pavilion facets and then leaks out from the sides or bottom of the diamond rather than reflecting ...

The cushion cut is an antique cut that most often resembles a cross between the Old Mine Cut (a deep cut with large facets that was common in the late 19th and the early 20th centuries) and a modern oval cut.

The same arguments concerning shallow and deep cut stones also hold for the other fancy shaped diamonds, although the proportions will be different. You can read about this subject in our article on fancy shapes.

Heavy Cut Crystal - crystal whose design is characterized by deep cuts or impressions.
Light Blown Crystal - crystal whose design is blown into a body that is essentially uniform with no cuts, etching or indentation (see Blown Glass).

This usually means a gemstone which has been cut too deep. This deep cut maximizes weight but sacrifices brilliance.
Depth
The height of a gemstone from the table to the culet which is measured in millimeters.

The faceting of a diamond in a shallow or deep cut allows for light to leave the diamond from the sides or the bottom as well as the table, thereby reducing the amount of light reflected from its table.

So while, low crown angles will produce higher brilliance, higher crowns or deep cut angles are used to deepen the colour. So for aquamarines, deep designs are always preferred and emerald cut is regarded as the most suitable for aquamarine.

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