Understanding Diamond Cut

Diamond Cut Guide

The Key to a Diamond's Brilliance & Fire

While often confused with "shape," Cut is the most critical factor in determining a diamond’s beauty. It refers to how well a diamond's facets interact with light. A high-quality cut can make a diamond look larger and more radiant, while a poor cut can make even a flawless stone look dull.

  • Brilliance The total white light reflected from a diamond's surface and interior.
  • Fire The dispersion of light into the colors of the spectrum (rainbow flashes).

The IGI Cut Grading Scale

For Round Brilliant diamonds, IGI uses a specific scale to measure light performance and optical symmetry.

Grade Performance Description
Ideal Maximum Sparkle The highest possible grade. Represents perfect proportions and maximum light return.
Excellent Superior Superior light return. Provides exceptional beauty and brilliance.
Very Good High Quality Reflects most light that enters, appearing radiant to the naked eye.
Good Average Reflects a significant amount of light, but lacks the intense fire of higher grades.
Fair / Poor Dull Appearance Light leaks through the sides, making the stone appear dark or lifeless.

Expert Recommendation

Cut has the greatest impact on a diamond’s appearance. Whether you choose a Natural or Lab-Grown stone, we recommend prioritizing an Ideal or Excellent cut to ensure your diamond sparkles from every angle.

The Elements of Cut

Diamond cut grade is determined by evaluating several technical components:

Proportions
The relationship between facet sizes and angles.
Symmetry
How precisely the diamond's facets align.
Polish
The smoothness of the diamond's surface.
Table %
The width of the top facet relative to the diamond.
Depth %
The total height of the stone from top to bottom.