Conversions
| U.S. Mesh | FEPA |
|---|---|
| 16/18 | D-1181 |
| 18/20 | D-1001 |
| 20/25 | D-851 |
| 25/30 | D-711 |
| 30/35 | D-601 |
| 35/40 | D-501 |
| 40/45 | D-426 |
| 45/50 | D-356 |
| 50/60 | D-301 |
| 60/70 | D-251 |
| 70/80 | D-213 |
| 80/100 | D-181 |
| 100/120 | D-151 |
| 120/140 | D-126 |
| 140/170 | D-107 |
| 170/200 | D-91 |
| 200/230 | D-76 |
| 230/270 | D-64 |
| 270/325 | D-54 |
| 325/400 | D-46 |
| Wide Range | |
| 16/20 | D-1182 |
| 20/30 | D-852 |
| 30/40 | D-602 |
| 40/50 | D427 |
| 60/80 | D252 |
| Size Designation | Normal Size Range |
|---|---|
| 1/4 | 0-1/ 2 |
| 1/2 | 0-1 |
| 1 | 0-2 |
| 2 | 1-3 |
| 3 | 2-4 |
| 4 | 2-6 |
| 5 | 4-6 |
| 6 | 4-8 |
| 8 | 6-10 |
| 10 | 8-12 |
| 12 | 8-16 |
| 15 | 10-20 |
| 17 | 12-22 |
| 20 | 15-25 |
| 25 | 20-30 |
| 30 | 22-36 |
| 35 | 30-40 |
| 45 | 36-54 |
| 50 | 40-60 |
| 67 | 54-80 |
| Wide Range | |
| 60 | 264 |
| 45 | 620 |
| 30 | 2,046 |
| 15 | 16,960 |
| 9 | 78,600 |
| 6 | 262,000 |
| 3 | 2,050,000 |
| 1 | 62,000,000 |
| Sieve Size U.S. Mesh | Micron Size | Aprox. no. of particles per carat (0.2 gm) |
|---|---|---|
| 16 | 1190 | 33 |
| 18 | 1000 | 57 |
| 20 | 841 | 97 |
| 25 | 707 | 160 |
| 30 | 595 | 282 |
| 35 | 500 | 460 |
| 40 | 420 | 770 |
| 45 | 354 | 1,334 |
| 50 | 297 | 2,080 |
| 60 | 250 | 3,240 |
| 70 | 210 | 6,140 |
| 80 | 177 | 10,400 |
| 100 | 149 | 17,140 |
| 120 | 125 | 20,920 |
| 140 | 105 | 49,400 |
| 170 | 88 | 83,400 |
| 200 | 74 | 140,000 |
| 230 | 63 | 252,000 |
| 270 | 53 | 384,000 |
| 325 | 44 | 660,000 |
| 400 | 37 | 1,130,000 |
| Micron | U.S. Mesh |
|---|---|
| 80-125 | 270/325 |
| 54-80 | 325/400 |
| 40-60 | 400/500 |
| 30-40 | 500/600 |
| 20-40 | 500/800 |
| 20-30 | 600/800 |
| 10-20 | 1200 |
| 8-12 | 1800 |
| 5-10 | 2200 |
| 4-8 | 3000 |
| 2-4 | 8000 |
| 1-2 | 13000 |
| 0-1 | 60000 |
| 0-1/2 | 100000 |
| Size | Avg. no. of Round Stones per carat |
|---|---|
| F | 128 |
| E | 106 |
| D | 84 |
| C | 77 |
| B | 70 |
| A | 62 |
| 1 | 58 |
| 2 | 50 |
| 3 | 40 |
| 4 | 30 |
| 5 | 25 |
| 6 | 20 |
| 7 | 15 |
| 8 | 11 |
| 9 | 9 1/2 |
| 10 | 7 |
| 11 | 5 2/3 |
| 12 | 4 1/2 |
| 13 | 3 1/2 |
| 14 | 3 |
| 15 | 2 2/3 |
| 16 | 2 1/16 |
| 17 | 1 5/6 |
| 18 | 1 2/3 |
| 19 | 1 1/3 |
Definitions
| Micron powder | Diamond powder usually prepared by methods of separation other then sieving |
| Undersize Particle | Any diamond particle smaller than the minimum of any size. |
| Silver’s | Fragile diamond particle of needle or rod like shape. |
| Shales | Diamond particle of thin plate like shape, which when seen through microscope, appear transparent. |
| Over Size | Those diamonds particles exceeding the maximum permissible size for any specific size range, they might be harmful to performance of the size range involved. |
| Particle size | Particle size determined by diameter of a circumscribed circle. |
| Size Determined by | 1. Circumscribed circle or 2. Mutually agreeable to buyer and seller. |
| Octahedron | A solid eight sided diamond with maximum of six points. |
| Cube | A six sided diamond with parallel sides. |
| Crystal | A Octahedron shaped diamond with flat sides and come to relatively sharp points at their intersection. |
| Elongated | A diamond generally cylindrical in shape |
| Maacles | A triangular shaped diamond with parallel flat sides. A generally triangular shaped diamond with convex sides. |
| Round | Spherical but with cubic crystalline structure. |
| Dodecahedron | A twelve sided diamond with rounded surfaces having six major & eight minor points. |