Diamond Cut

The GIA Diamond Cut Grade

The Diamond Cut Grade refers to how well the diamond has been cut from the rough. The cut is considered to be the most important attribute of a diamond. The cut of a diamond determines a diamond's brilliance. So the better the cut, the more a diamond will sparkle and reflect the light.

The illustrations below demonstrate different light returns based on quality of cut.

How a diamond is awarded a Cut Grade

The diamond is placed in a Sarin machine which measures its proportions and angels. Depending on the result, the diamond will be given an appropriate cut grade. The Gemmological Institute of America (GIA) introduced the cut grade on 1st January 2006 for the Round Brilliant diamond. Currently there is no other cut grade for other diamond shapes. The options for the cut grade from the GIA are: Poor, Fair, Good, Very Good and Excellent.

At Steven Stone, in order to maintain our high reputation for excellence and to consistently exceed customer expectations, we only offer the top three cut grades: Good, Very Good and Excellent.

An Excellent Cut is sometimes referred to as an Ideal Cut diamond. This means that the diamond is perfectly proportioned. Ideal Cut grades generally apply to Round Brilliant diamonds, but sometimes it is possible to obtain other shapes that adhere to this standard. Ideal Cut diamonds are normally around 5-10% more expensive than the average cut.

Diamond Cut - Symmetry & Polish

The symmetry grade is also important when considering which diamond you wish to purchase. This grade indicates how well the diamond facets are aligned. The symmetry of a diamond also determines the amount of light returned to the eye, i.e. the sparkle. The options for the symmetry and polish grade established by the GIA are: Poor, Fair, Good, Very Good and Excellent. Again, Steven Stone we only offer the top three symmetry and polish grades. These are: Good, Very Good and Excellent.

The polish grade is not as important as the symmetry or cut grade. This is because it has only minimal impact on a diamond’s light return. The polish grade refers to the smoothness of the diamond’s facets. If the grade of polish is Poor or Fair, the diamond may appear slightly blurred or dull. We would therefore recommend that the polish grades you should consider when selecting your diamond are either Very Good or Excellent.