Length, width and outline determine a diamond’s face-up footprint. Carat records its weight. Read those dimensions alongside depth to understand where the weight is carried.
Read all three measurements
Reports list length × width × depth in millimetres. Length and width describe the visible footprint. Depth shows how much stone sits below the table. A deeper stone can carry weight where it disappears into the setting.
Six real dossier examples
The final column below multiplies length by width as a simple comparison aid. It describes the enclosing rectangle; curved corners and individual outlines make the actual face-up area smaller.
| Public dossier | Measurements, mm | L/W | L × W proxy, mm² |
|---|---|---|---|
| 2.01 ct H SI1 | 6.84 × 6.51 × 4.90 | 1.05 | 44.53 |
| 2.03 ct F VS1 | 6.97 × 6.45 × 5.06 | 1.08 | 44.96 |
| 2.13 ct D IF | 7.74 × 6.52 × 4.68 | 1.19 | 50.46 |
| 5.01 ct H VS1 | 10.85 × 9.39 × 6.32 | 1.16 | 101.88 |
| 8.01 ct H VVS2 | 11.72 × 11.60 × 7.14 | 1.01 | 135.95 |
| 9.04 ct F IF | 14.45 × 12.02 × 6.56 | 1.20 | 173.69 |
The near-two-carat group shows the point clearly. The 2.01 ct and 2.03 ct stones have almost identical proxies. The 2.13 ct stone carries only about five to six percent more weight, yet its longer outline gives a proxy roughly twelve percent larger. Compare that extra spread with each stone’s profile and movement.
Use ratio to describe shape
Length divided by width describes squareness or elongation. Photographs show the corners, shoulders and small asymmetries. Compare the near-square 8.01 ct stone at 1.01 with the elongated 9.04 ct stone at 1.20. The first feels concentrated; the second covers more distance along one axis.
Depth can hide weight
A high crown, deep pavilion or thick girdle can add depth. Ask how that depth relates to brightness, fire, obstruction and face-up spread. Use the Old Mine Cushion proportions guide to read the complete proportion set.
Balance spread with profile and movement
A broad footprint can be desirable, but maximum spread may cost crown height, pavilion structure or durability. Judge spread beside movement, contrast, outline, condition and the intended setting.
A quick comparison method
- Match the report and measurements to each stone.
- Compare actual length and width in millimetres.
- Use L/W to describe the outline.
- Review depth and side profile.
- Watch both stones under matched lighting and scale.
- Consider how each outline will sit in the setting.
The antique diamond evaluation guide explains the video and lighting sequence.
Request a side-by-side comparison
Ask for equally scaled photographs, matched movement video and the available reports for the stones you are considering. Request a private diamond search.
Editorial review: Updated 3 September 2026 from public Imperial Cushions dossiers and GIA educational material. Measurements and availability should be reconfirmed before purchase.
Sources: GIA Guide to Understanding a Diamond Grading Report; GIA: Understanding Carat Weight; GIA: Diamond Cut Grading Q&A.