Diamond Sieve Size Chart
Melee diamond sizes by sieve, with millimetres, approximate carat weight per stone and stones per carat. Work out how many stones are in a parcel, or how many carats you need.
| Sieve | Diameter (mm) | Carat per stone | Stones per carat |
|---|---|---|---|
| +000 / −0 | 1.00 – 1.10 | 0.005 | 200 |
| +0 / −1 | 1.10 – 1.15 | 0.006 | 167 |
| +1 / −1.5 | 1.15 – 1.20 | 0.007 | 143 |
| +1.5 / −2 | 1.20 – 1.25 | 0.008 | 125 |
| +2 / −2.5 | 1.25 – 1.30 | 0.009 | 111 |
| +2.5 / −3 | 1.30 – 1.35 | 0.010 | 100 |
| +3 / −3.5 | 1.35 – 1.40 | 0.011 | 91 |
| +3.5 / −4 | 1.40 – 1.45 | 0.012 | 83 |
| +4 / −4.5 | 1.45 – 1.50 | 0.013 | 77 |
| +4.5 / −5 | 1.50 – 1.55 | 0.014 | 71 |
| +5 / −5.5 | 1.55 – 1.60 | 0.016 | 62 |
| +5.5 / −6 | 1.60 – 1.70 | 0.018 | 56 |
| +6 / −6.5 | 1.70 – 1.80 | 0.021 | 48 |
| +6.5 / −7 | 1.80 – 1.90 | 0.025 | 40 |
| +7 / −7.5 | 1.90 – 2.00 | 0.029 | 34 |
| +7.5 / −8 | 2.00 – 2.10 | 0.035 | 29 |
| +8 / −8.5 | 2.10 – 2.20 | 0.039 | 26 |
| +8.5 / −9 | 2.20 – 2.30 | 0.044 | 23 |
| +9 / −9.5 | 2.30 – 2.40 | 0.052 | 19 |
| +9.5 / −10 | 2.40 – 2.50 | 0.058 | 17 |
| +10 / −10.5 | 2.50 – 2.60 | 0.069 | 14 |
| +10.5 / −11 | 2.60 – 2.70 | 0.074 | 14 |
| +11 / −11.5 | 2.70 – 2.80 | 0.078 | 13 |
| +11.5 / −12 | 2.80 – 2.90 | 0.086 | 12 |
| +12 / −12.5 | 2.90 – 3.00 | 0.095 | 11 |
| +12.5 / −13 | 3.00 – 3.10 | 0.108 | 9 |
| +13 / −13.5 | 3.10 – 3.20 | 0.116 | 9 |
| +13.5 / −14 | 3.20 – 3.30 | 0.130 | 8 |
| +14 / −14.5 | 3.30 – 3.40 | 0.145 | 7 |
| +14.5 / −15 | 3.40 – 3.50 | 0.155 | 6 |
| +15 / −15.5 | 3.50 – 3.60 | 0.165 | 6 |
| +15.5 / −16 | 3.60 – 3.70 | 0.190 | 5 |
| +16 / −16.5 | 3.70 – 3.80 | 0.200 | 5 |
Round brilliant melee. Weights are approximate averages; real parcels vary with cut, depth and girdle.
What Is a Diamond Sieve Size?
Melee is the trade name for small diamonds, roughly 1 to 3.8 mm across and up to about 0.20 ct. They are too small and too numerous to measure one by one, so they are sorted with sieve plates: metal plates drilled with round holes of a set size, stacked from large to small. Each stone falls through until it reaches a plate whose holes are too small for it.
A sieve size is written as a pair of plate numbers. +6.5 / −7 means the stones passed through plate 7 but were held by plate 6.5, so every stone in the parcel is between those two hole sizes, here about 1.80 to 1.90 mm. The plate numbers are a trade convention, not millimetres.
How to Use the Chart
Choose a sieve size, or type a diameter to find it, then enter a number of stones to see the approximate total weight, or switch to Carats to see roughly how many stones a given weight contains. This is how melee is usually ordered and quoted: by sieve size and total carat weight.
For a pavé or halo design, count the stones in the CAD model or the setting drawing, add a few spares for breakage and replacements, and use the total weight to compare quotes.
How Accurate Are the Weights?
The millimetre ranges follow the standard sieve plate sizes. The weight per stone is an average for well-proportioned round brilliant melee, and it matches our Diamond Size Chart. Published sieve charts differ by 10 to 20% on weight, because melee is cut to many different depths and girdle thicknesses, and some suppliers use their own plates. Always agree the millimetre range and the total weight with your supplier, and check a parcel with a gauge and a carat scale before setting.
Natural and laboratory-grown diamonds of the same size weigh the same. Single cut and full cut melee of the same diameter can differ slightly in weight, and fancy shapes such as baguettes and princess cuts are sold by millimetre size rather than by sieve.