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Diamond Weight (Carat) Calculator

Estimate a round diamond's carat from its diameter.

Calculated Output

Estimated weight (carats) 1

Formula: carat ≈ (diameter ÷ 6.5)³

Step-by-Step Breakdown

1. Values used:

2. Diameter = 6.5

4. Estimated weight = 1carats

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The math behind it

A 6.5 mm round brilliant is about 1 carat; weight scales with diameter cubed: carat ≈ (mm ÷ 6.5)³.

6.5 mm → ~1.0 carat.

Exact?

Cut depth and shape change it — this is an estimate for round brilliants.