The Pentafan is a cut designed for larger gems with deep color saturation. You’ll get a lot of use from this cut, since there aren’t many suited for this purpose.
By D. R. Jerkins 1 minute read

Flashes from a Dark Gemstone

Pentafan Design - Almandine Garnet

Pentafan-cut almandine by D. R. Jerkins.

To the right, you have 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.

Diagrams

Pentafan Design - Diagrams

Pentafan Cutting 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

A note from Donald Clark: D. R. Jerkins apologized that he couldn’t send us an example of the Pentafan gem design sooner. As it turned out, the gems sold out too quickly. Now that’s a problem we should all have!