The Pentafan Design For Gemstones
by
The Pentafan design is a cut for larger gems with deep color saturation. You’ll get a lot of use from this cut, since there are not many suited for this purpose. Shown here is an almandine garnet, one of the most difficult gemstones to facet for brilliance. Even though the color saturation was quite deep, it turned out to be a great performer. There are continuous flashes of color as the gem is moved.
By bringing the pavilion facets to a point at the corners of the girdle, instead of at the culet, the play of light is greatly altered. There is also a uniform dispersion of light throughout the stone, instead of the standard bright center surrounded by dark regions.
Pentafan Design: Diagrams
Pentafan Design: Instructions
Pavilion
| Step | Angle | Index | Notes |
| 1 | 40º | 120-024-048-072-096 | Cut to PCP |
| 2 | 40.4º | 002-022-026-046-050-070-074-094-098-118 | Locate Corners |
| 3 | 41.5º | 004-020-028-044-052-068-076-092-100-116 | Meet P1, P2 @ Corner |
| 4 | 43.5º | 006-018-030-042-054-066-078-090-102-114 | Meet P1, P2, P3 @ Corner |
| 5 | 46.9º | 008-016-032-040-056-064-080-088-104-112 | Meet P1, P2, P3, P4 @ Corner |
| 6 | 61º | 012-036-060-084-108 | Meet Others @ Corners |
| 7 | 90º | 012-036-060-084-108 | Set/Level Girdle |
Crown
| Step | Angle | Index | Notes |
| 1 | 19º | 120-024-048-072-096 | Set Girdle Thickness |
| 2 | 45º | 012-036-060-084-108 | Level Girdle |
| 3 | 12º | 006-012-018-030-036-042-054-060-066-078-084-090-102-108-114 | Meet C1, C2, C1 form TCP |
| 4 | 0 | Table | Meet C3, C1, C3 |
