The diamond is adjudged too shallow or too deep depending on the relative size between the diamond depth and the diamond diameter.
Different varieties of a stone diamond ring could be cut in different depths depending upon the need. Below is a quick look at what happens when a diamond is cut too shallow or too deep.
When the Diamond is Cut Too Shallow
When the diamond cut is too shallow, light enters the pavilion at a low angle. It passes through the diamond and exits through either side. Thus, it does not reflect through the table and completely misses your eyes. Although shallow diamonds appear large based on their table size, the escape of light through the bottom causes a big reduction in the diamond’s fire, brilliance, and sparkle.
When the Diamond is Cut Too Deep
When the diamond is cut too deep, light strikes the pavilion at a much sharper angle, which reflects it to another pavilion. Subsequently, light is forced to pull back and exit through the bottom. This makes the diamond appear dull. Hence, it loses its inherent vibrancy and radiance, apart from having a contracted appearance in comparison to the normal cut diamond.