Traditional Diamond Cut Grading Methods


Step 4: Gem Grading

Lesson 15

Why Learn Traditional Diamond Cut Grading Methods?

In 2005, the Gemological Institute of America (GIA) released a new, modern method for evaluating diamond cuts. However, beginning gemologists should learn traditional diamond cut grading for two reasons.

  • You’ll likely come across grading reports that utilize older methods. They’ve been used on thousands of reports that will be around for many years to come.
  • Learning traditional diamond cut grading will show you how to evaluate cuts by eye. When you examine diamonds away from your shop, you’ll need something to fall back on.

The Ideal Cut (May Not be Ideal)

Of the Four Cs of gem grading, cut ranks as the most important for diamonds. The cut (or make) determines why one diamond features spectacular fountains of light, while another looks lifeless and dull. You’ll find volumes and volumes written about cut. That’s a shame. In truth, the principles involved are really quite simple, as are traditional diamond cut grading techniques.

The essential problem of evaluating the cut revolves around determining the ideal cut for a diamond. Today, most experts agree, within a small range, on what an ideal cut is. The …

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Full Article Details


Content Length 6255 words
Reading time 31 min 16 sec

Here's what you get if you unlock this article:

  • Why Learn Traditional Diamond Cut Grading Methods?
  • The Ideal Cut (May Not be Ideal)
    • An Ideal Cut Versus a Swindle Cut
  • What Makes a Well-Cut Diamond?
    • The Pavilion
    • Crown Facets
    • From Rough to Cut Diamonds
    • The Swindle Cut
  • Ideal Cut Diamond Proportions
    • GIA Diamond Cut Classes
    • AGS Diamond Cut Grades
    • Notes on the GIA, AGS, and IGS Standards
  • Math Review
    • Percentages
    • Averages
  • Evaluating the Cut
  • Proportion Analysis
    • Stone Diameter
    • Table Width
      • Using Magnification
      • Visual Estimation Techniques
      • The Bowing Technique
      • Refining Your Visual Estimation of Table Width
      • Refining Your Bowing Technique
      • An Example of Estimating Table Width
    • Crown Angle
      • Profile Method
      • Face Up Method
      • Crown Height Percentage (AGS)
      • AGS Crown Height Percentage Chart
    • Pavilion Depth Percentage
      • Measuring Pavilion Depth
      • Sight Estimate for Pavilion Depth
      • Refining Your Pavilion Depth Estimations
      • Culet Adjustment
    • Girdle Thickness
      • Thickness Variations
      • AGS and GIA Girdle Grading Differences
      • Girdle Terms
    • Culet Sizes
      • Culet Terms
  • Total Depth Percentage
  • Finish
    • Classing Features Under Finish or Clarity?
    • Polish
    • Symmetry
      • Table and Culet Centering Errors
      • Girdle Errors
      • Facet Errors
      • Symmetry Terms
      • Major Symmetry Problems
    • Summarizing Finish
      • Polish Categories
      • Symmetry Categories
  • Assigning a Class

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