Also known as diamond profile projectors, these grading tools are designed for precise measurement of diamond cut proportions, including table width ratio, pavilion depth ratio, total depth ratio, crown height ratio, girdle thickness, table and culet symmetry, and roundness. They are suitable for analyzing both loose diamonds and finished stones ranging from 0.1 to 4 carats.
Used to assess the proportions of round brilliant-cut diamonds, these tools provide accurate measurements of parameters such as table width, pavilion depth, crown height, girdle thickness, and crown angles, ensuring consistency and precision in diamond grading.
Diamond proportion scopes consist of a main unit, projection magnification system, magnetic screen, zoom objective lens, focusing objective lens, power switch, and horseshoe-shaped sample holder.
| Parameter | Good | Very Good (VG) | Excellent (EX) | Very Good (VG) | Good |
| Table percentage | 47-49 | 50-51 | 52-62 | 63-66 | 67-69 |
| Crown height percentage | ≤8.5 | 9.0-10.5 | 11.0-16.0 | 16.5-18.0 | ≥18.5 |
| Girdle thickness percentage | 0-0.5 | 1.0-1.5 | 2.0-4.5 | 5.0-7.5 | ≥8.0 |
| Pavilion depth percentage | ≤39.5 | 40.0-41.0 | 41.5-45.0 | 45.5-46.5 | ≥47.0 |
| Total depth percentage | ≤55 | 55.0-57 | 57.5-60 | 60-62 | ≥65 |
| Star facet length percentage | < 40 | 40-45 | 45-65 | 65-70 | ＞70 |
| Lower girdle facet length percentage | < 65 | 70-85 | ＞90 | ||
| Crown angle (°) | 26-30 | 30-31 | 31.5-36.5 | 37-38 | 38-40 |
| Pavilion angle (°) | 38.2-38.8 | 39.8-40.4 | 40.4-41.8 | 42-42.4 | 42.6-43 |
Our team is ready to assist you with gemological instruments and solutions for precise gemstone analysis.
Gemological Instruments
