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Calcimator

Faceting Angle Calculator

Calculate optimal crown and pavilion angles for different gem cuts based on refractive index.

Inputs

Results

Optimal Pavilion Angle

43.37°

Critical Angle40.37°
Pavilion Min42.37°
Pavilion Max46.37°
Crown Angle42°
Cut StyleStandard Brilliant
Table %55%
GirdleMedium (2-4%)
How to Use This Calculator
  1. Enter the Refractive Index of the gem material (diamond = 2.42, sapphire = 1.77, quartz = 1.55).
  2. Select the Cut Style: standard brilliant, Portuguese, Barion, or step cut.
  3. Review the Optimal Pavilion Angle for total internal reflection and the Critical Angle.
  4. Check the Crown Angle, Table Percentage, and Girdle Thickness recommendations.
  5. Use the pavilion angle range to set your faceting machine for the first row of pavilion facets.

How the result changes with Refractive Index

Refractive IndexOptimal Pavilion Angle
1.4745.86°
1.934.76°
2.4127.52°
2.8323.69°

What each input means

Refractive Index
Refractive index of the gem material (Quartz=1.544, Diamond=2.417)
Cut Style
Faceting design style

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Refractive Index = 1.544, Cut Style = 0 = 2 input(s) provided
  2. Calculate Optimal Pavilion Angle
    Optimal Pavilion Angle
    43.37 = 43.37
  3. Calculate Critical Angle
    Critical Angle
    40.37 = 40.37
  4. Calculate Pavilion Min
    Pavilion Min
    42.37 = 42.37

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