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Carats = mm² / 0.485 (for round diamonds approx)
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The mm to carat conversion calculates the approximate weight of a gemstone (in carats) based on its face-up area in square millimeters. This is particularly useful for round diamonds and other gemstones where direct weight measurement may not be available.
The calculator uses the conversion formula:
Where:
Explanation: This formula provides an approximate conversion from surface area to carat weight, specifically calibrated for round brilliant cut diamonds.
Details: Accurate carat estimation from measurements is crucial for gemstone valuation, jewelry design, and when direct weighing is not possible. It helps in comparing stones and making informed purchasing decisions.
Tips: Enter the area of the gemstone in square millimeters. For round stones, area can be calculated as π × (diameter/2)². Ensure the area value is positive and measured accurately.
Q1: How accurate is this conversion?
A: This conversion provides an approximation. Actual carat weight can vary based on cut quality, depth percentage, and stone shape. For round diamonds, it's generally within 5-10% accuracy.
Q2: Does this work for all gemstone shapes?
A: The formula is optimized for round brilliant cuts. Other shapes (oval, princess, emerald) have different conversion factors due to varying depth-to-width ratios.
Q3: What if I only have diameter measurements?
A: For round stones, calculate area first: Area = π × (diameter/2)². Then use that area value in the calculator.
Q4: Why is the conversion factor 0.485?
A: This factor accounts for the typical depth percentage and density of diamonds. It's derived from empirical data for well-cut round brilliant diamonds.
Q5: Can this be used for colored gemstones?
A: Different gemstones have different densities, so the conversion factor varies. For example, sapphires and rubies would require a different factor due to their higher density.