Choosing and executing diamond cuts successfully takes an understanding of light and angles. No wonder famed diamond cutter Marcel Tolkowsky was also a mathematician! Cutting is critical to the optical performance of diamonds. Unfortunately, when most people view a diamond, carat size usually makes the biggest impression. In reality, cut greatly affects how large a diamond appears and the light pattern it shows. It also largely determines its brilliance — how much light it returns — and dispersion — how much internal “fire” it displays. If poorly executed, the cut can ruin these most prized aspects of diamonds – not something you want in an engagement ring!

Diamond Cut Grades

For round brilliant diamonds, cut grades are as follows:

  • Excellent
  • Very good
  • Good
  • Fair
  • Poor

Lasers do most of the cutting nowadays, so most diamonds should fall in the Very Good to Excellent range.

The only reason diamonds ever have a less than Excellent cut is because the diamond cutter is trying to save weight. Diamond cutting is usually a compromise between saving weight and maintaining good brightness, pattern, and symmetry.

A diamond of a larger carat size simply commands a higher price despite having a somewhat lower cut…