Cut is the geometric proportions like symmetry, polish and facet proportion of a diamond, such as brilliant Cut. Cut does not refer to shape (pear, oval), but the symmetry, proportioning and polish of a diamond. The cut of a diamond greatly impacts diamond brilliance, this means if it is cut poorly, it will be less luminous.

Fair Not as brilliant as a Good cuts or above, Fair diamond cuts are still considered good quality diamonds.

Good Good light performance. Reflects most of the light that enters. Good diamond cuts are far less pricey than Very Good cuts.

Ideal Excellent light performance. Reflects almost all of the light that enters.  An exquisite and rare cut.

Poor Diamonds that are generally so deep and narrow or shallow and wide that they lose most of the light out the sides and bottom.

Very Good It reflects much of the light that enters for superior brilliance and sparkle nearly as much as the Ideal cut, creating outstanding value.