mm to Carat Conversion
Convert diamond dimensions between millimeters and carat weight
Diamond Size Conversion
For round diamonds, depth is typically 60% of diameter
Adjustments (Optional)
1.0 = thin, 1.01-1.03 = medium, 1.03-1.06 = thick
Example Conversions
Round Diamond Example
Dimensions: 6 mm diameter × 2 mm depth
Calculation: 6² × 2 × 0.0061 × 1 = 0.439 carats
Weight: 0.439 ct = 87.8 mg = 0.088 g
Princess Cut Example
Dimensions: 5 mm × 5 mm × 3 mm
Calculation: 5 × 5 × 3 × 0.0083 × 1 × 1 = 0.623 carats
Weight: 0.623 ct = 124.5 mg = 0.125 g
Two Carat Examples
Round: 12.5 mm diameter × 2 mm depth
Asscher: 9 mm × 9 mm × 3 mm
Marquise: 13 mm × 11 mm × 2.5 mm
Carat Conversion Facts
Girdle Thickness Guide
Very Thin/Thin
Factor: 1.00 - 1.01 (0%-1% of diameter)
Medium
Factor: 1.01 - 1.03 (1%-3% of diameter)
Thick/Very Thick
Factor: 1.03 - 1.06 (3%-6% of diameter)
Extra Thick
Factor: >1.06 (>6% of diameter)
Understanding Diamond Size and Weight Conversion
Why Convert mm to Carats?
The carat is the standard unit of mass for gemstones and pearls. While you can measure a diamond's dimensions in millimeters, its value is primarily determined by weight in carats. This conversion helps estimate a diamond's weight from its physical dimensions.
Accuracy Considerations
- •Different shapes have different density coefficients
- •Girdle thickness affects overall weight
- •Shape irregularities require correction factors
- •Results are estimates, actual weight may vary
Shape Correction Factors
Wide/Fat Features
Pear: +1% to +5%
Marquise, Oval, Heart: +1% to +10%
Large Culet
All shapes: +1% to +2%
Wide Corners
Emerald, Radiant: -1% to -5%
Pavilion Bulge
Emerald, Radiant, Trillion: +1% to +18%
Important Notes
- • These calculations provide estimates. Professional certification requires precise measurement equipment.
- • All dimensions must be in millimeters for accurate calculations.
- • Results can vary ±5-10% from actual weight due to cutting variations and measurement precision.
- • For insurance or appraisal purposes, always use certified measurements from reputable gemological laboratories.
- • The tool works bidirectionally - you can convert mm to carats or carats to mm.