How Many Carats Is A 5 mm Diamond?
A 5 mm round brilliant weighs about 0.47 ct. See how depth changes it, the weight in grams and cents and the sizes around it, then adjust the stone below.
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Round brilliant estimate. Size charts from Stuller (May 2025) and Walt's Jewelers, checked 9 November 2026.
Your stone
Shape
Measured across the girdle. On a certificate, average the smallest and largest diameter.
Table to culet, in mm or as a % of the diameter. Leave it blank to assume 61%, typical for a well-cut round.
Estimated weight
Round, 5 mm
0.47 ct
About 0.093 g · 47 cents
- Formula
- 5² × 3.05 × 0.0061
- Total depth
- 3.05 mm (61.0%)
- At 59–63% depth
- 0.45–0.48 ct
- In grams
- 0.093 g
- In cents (points)
- 47
Typical sizes for well-cut rounds
| Weight | Trade charts | Formula, 61% |
|---|---|---|
| 0.33 ct | 4.4 mm | 4.46 mm |
| 0.40 ct | 4.8 mm | 4.75 mm |
| 0.50 ct | 5.2 mm | 5.12 mm |
Diameters from Stuller's size chart (2025) and Walt's Jewelers' chart. The closest is highlighted.
An estimate from the stone's measurements. A thick girdle or a bulging pavilion adds weight; weigh a loose stone to be sure.
How to use it
Measure the stone across the girdle. 5 mm is filled in for you; change it to your stone's size.
Add the total depth from the certificate if you have it, or leave it blank to assume 61%.
Read the weight in carats, grams and cents, and compare it with the trade charts.
5 mm round diamond weight at a glance
A 5 mm round brilliant cut to a typical 61% depth (3.05 mm) weighs about 0.47 ct by the standard formula: 5 × 5 × 3.05 × 0.0061. That is 0.093 g, or 47 cents. Trade size charts from Stuller and Walt's Jewelers put a 5 mm round at about 0.45–0.47 ct.
Weight by depth
| Depth | Depth in mm | Weight |
|---|---|---|
| 59% | 2.95 mm | 0.45 ct |
| 61% | 3.05 mm | 0.47 ct |
| 63% | 3.15 mm | 0.48 ct |
A deeper stone hides more of its weight below the girdle, so it faces up smaller for its weight. Well-cut rounds are usually between about 59% and 63%.
Sizes around 5 mm
| Diameter | At 61% depth | At 59–63% | Cents |
|---|---|---|---|
| 4.7 mm | 0.39 ct | 0.37–0.40 ct | 39 |
| 4.8 mm | 0.41 ct | 0.40–0.43 ct | 41 |
| 4.9 mm | 0.44 ct | 0.42–0.45 ct | 44 |
| 5 mm | 0.47 ct | 0.45–0.48 ct | 47 |
| 5.1 mm | 0.49 ct | 0.48–0.51 ct | 49 |
| 5.2 mm | 0.52 ct | 0.51–0.54 ct | 52 |
| 5.3 mm | 0.55 ct | 0.54–0.57 ct | 55 |
Other shapes and sizes
For an oval, pear, princess or other fancy shape, or to find the size for a carat weight, use the diamond mm to carat calculator. One size down is 4.5 mm; one size up is 5.5 mm.
FAQ
Questions
How many carats is a 5 mm round diamond?
About 0.47 ct by the standard formula (diameter² × depth × 0.0061) with a typical 61% depth of 3.05 mm. Trade size charts from Stuller and Walt's Jewelers put a 5 mm round at about 0.45–0.47 ct.
How much does depth change the weight of a 5 mm diamond?
At 59% depth (2.95 mm) it weighs about 0.45 ct and at 63% (3.15 mm) about 0.48 ct, a spread of about 7%. That is why two 5 mm stones can be sold as different weights. Enter the real depth in the calculator for a closer figure.
What is a 5 mm diamond in grams and cents?
About 0.093 g and 47 cents (points), because 1 carat is 0.2 g and 100 cents.
How do I check that a diamond is really 5 mm?
Measure across the girdle with a millimetre gauge, or read the measurements on the grading report, written like 4.98–5.02 × 3.05 mm (smallest and largest diameter × depth). Use the average diameter and the total depth in the calculator.
Does a 5 mm lab-grown diamond weigh the same?
Yes, if it is cut the same. Lab-grown and natural diamonds are the same material with the same density, so a 5 mm lab-grown round at 61% depth also weighs about 0.47 ct. Moissanite weighs less and cubic zirconia more at the same size.
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