The Pentafan Design For Gemstones


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.

Pentafan Design - Almandine Garnet
D. R. Jerkins apologized that he couldn’t send us an example of the Pentafan design sooner. The gems sold out too quickly. Now that’s a problem we should all have!

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 - Diagrams

Pentafan Design: Instructions

Pavilion

StepAngleIndexNotes
140º120-024-048-072-096Cut to PCP
240.4º002-022-026-046-050-070-074-094-098-118Locate Corners
341.5º004-020-028-044-052-068-076-092-100-116Meet P1, P2 @ Corner
443.5º006-018-030-042-054-066-078-090-102-114Meet P1, P2, P3 @ Corner
546.9º008-016-032-040-056-064-080-088-104-112Meet P1, P2, P3, P4 @ Corner
661º012-036-060-084-108Meet Others @ Corners
790º012-036-060-084-108Set/Level Girdle

Crown

StepAngleIndexNotes
119º120-024-048-072-096Set Girdle Thickness
245º012-036-060-084-108Level Girdle
312º006-012-018-030-036-042-054-060-066-078-084-090-102-108-114Meet C1, C2, C1 form TCP
40TableMeet C3, C1, C3