Cut is the characteristic of a diamond that gives it the fire and brilliance that diamonds are known for. When a diamond is cut too shallow, when compared to it's diameter, the light striking the table top and / or the crown facets can pass through the stone without being refracted and the diamond will have a dull brilliance. In some severe cases a black center is caused, known in the diamond industry as a fish eye. A similar effect of being dull or a "flat looking diamond" is caused when the diamond has a very deep pavilion depth when compared to it's diameter. However when the proportions approach the industry standard of an "ideal cut", the colors of the prismatic effect give the beholder a light show of intense brilliance and wonder. The diamonds that show this effect off the best are often referred to as "Hearts and Arrows" and will always sell for a premium due to the care and skill that has gone into their creation.