Lucifer by Jack Rowland

Lucifer - designed by Jack Rowland
Modification of Triangle twist by Charles Johnston
as published in Diagrams for Faceting Volume III by Glenn & Martha Vargas
Angles for R.I. = 1.54 31 facets + 6 facets on girdle = 37
3-fold symmetry 96 index
L/W = 1.155 T/W = 0.528 T/L = 0.457 P/W = 0.533 C/W = 0.185
H/W = (P+C)/W+0.02 = 0.737 P/H = 0.723 C/H = 0.250
Vol./W^3 = 0.287

g1 90.00 16-48-80 CAM angle 35
g2 90.00 96-32-64 CAM angle 27.5
c 42.00 06-13-19-26-38-45-51-58-70-77-83-90 Cut to center point
b1 60.00 96-32-64 Cut to g1-g2-c meet
b2 70.00 16-48-80 Cut to g1-g2-c meet

B1 51.00 16-48-80 Leave some girdle
B2 37.00 17-49-81 Cut to g1-g2-B1 meet
M1 27.00 20-52-84 Cut to B1-B2-girdle meet
B3 34.50 96-32-64 Cut to B2-M1 top meet & level girdle
T 00.00 Table Cut to M1-B2-B3 meet
Note: B3 facet may need some fine angle adjustment depending on how accurate the other facets are cut.

Download PDF format printer friendly cutting instructions: [ download icon lucifer printer icon ]

Download the GemCad format design file: [ download icon lucifer.gem ]

The devil you say! Lucifer is also known as the light bearer. I don't think I could have come up with a better name for this fiery gem. This is a super nice triangle. It is bright, has lots of action, and is one of the simpler gems to cut. Beginners should not be afraid to try this one. It is also very unusual with it's asymmetric crown.

I ran across a cut called Triangle Twist by Charles Johnston in Diagrams for Faceting v3 (1987) p38 by Glenn and Martha Vargas. I was very pleased with Triangle Twist, but the corners were rather dark. This isn't a big problem as the setting will cover this to some degree. Always looking for a challenge, I decided to try to improve it.

After a little work with GemCad tracing why the light leaked out at the corners I discovered something quite remarkable. The dark corners were caused by too many facets! I re-designed the pavilion to remove the offending facets and improved the gem's brightness by 15%! This gem I've dubbed "Lucifer" and it is also easier to cut.

Start with a CAM PREFORM cutting using the girdle index settings and the CAM angles listed with the girdle. Cut to a center point, then level the girdle all around using these facets as a basis. This will give you a perfect preform. Next, cut the CAM facets completely away using the c facets. Cutting should continue without problems from there.

When you get to the B3 facet you may need to adjust the angle up or down a few degrees to make both the table and girdle meets. Just watch closely as you cut and adjust accordingly as the facet approaches either the girdle or the table meets. If you are not hung up on meetpoint faceting, skip the preform and cut c facets to a common center point, then cut the girdle facets to the proper width by eye and level the girdle with the b facets. You will have to adjust the B3 crown facet angle on the a little, but this is no big deal.

I also learned something significant about GemCad with this cut. When I cut the gem design it ended up a mirror image of the design. This was a result of my not understanding one of the many facets of GemCad. For most gems it doesn't matter if your index is right or left handed, but for asymmetric gems like Triangle Twist it does. GemCad defaults to an index the reverse of mine, thus the mistake. This, coupled with my tendency toward dyslexia created the confusion. A negative gear index needs to be selected for most facet machines if the index numbers increase in the clockwise direction.

A quick note on setting this gem. Normal triangle settings won't fit this. I finally used a "Miracle Mount" available from Tripps. I ground down one end to fit the narrow end of the gem. This was an unusual setting for an unusual stone, and it really shows off the gem.

Index of Gem Designs

Perfect Transfer Index

Table of Contents

Bob Keller