Don Clark's Nightmare by Carl R. Downey

Nightmare - designed by Carl Downey 1/98 alckytxn@flash.net
Designed for Beginning to Intermediate Faceters
Based on 19 main designs in 'Faceting the Easy Way' by Don Clark
Angles for R.I. = 1.54 77 facets + 19 facets on girdle = 96
1-fold, mirror-image symmetry 96 index
L/W = 1.001 T/W = 0.542 T/L = 0.541 P/W = 0.446 C/W = 0.163
H/W = (P+C)/W+0.02 = 0.629 P/H = 0.709 C/H = 0.259
Vol./W^3 = 0.218 Brightness at 0 degrees tilt for quartz
COS = 83.6 ISO = 91.6

Pavilion
1 42.00 96-05-10-15-20-25-30-35-40-45-51-56-61-66-71-76-81-86-91 Meet at perm. culet point
2 90.00 96-05-10-15-20-25-30-35-40-45-51-56-61-66-71-76-81-86-91 Establish girdle position and width
Crown
M 36.04 96-05-10-15-20-25-30-35-40-45-51-56-61-66-71-76-81-86-91 Level girdle
S1 35.00 02-03-07-08-12-13-17-18-22-23-27-28-32-33-37-38-42-43-
53-54-58-59-63-64-68-69-73-74-78-79-83-84-88-89-93-94
Meet M-2-2-M (watch those indexes!)
S2 34.75 47-49 Meet M-2-2-M
T 00.00 Table Meet S1-S1...S1-S2-S1...etc.

Nightmare Design Notes
By Carl R. Downey, 1 Lucky Texan

Having read about the potential brilliance gains when cutting stones with odd numbered main facets, I was pleased to discover in the book Modern Faceting the Easy Way by Don Clark, a way to use a 96 index gear to cut 19 main facets. Several of the designs in the book have helped me increase recovery in expensive rough but most have simple step facets on the crown.

A cut with a single tier of 19 main facets for the pavilion and a step faceted crown is very bright (due to 'decreased opportunities for light extinction' - I am told) but somewhat - uhm...shall we say wearisome - after 3-4 stones. I wanted to keep the pavilion but decided to 'busy up' the crown. A little tricky to get it through GemCad but worked out fairly well. I have cut a Dinnerbucket Creek garnet and a chrome tourmaline (which showed RED highlights!) both with somewhat lower pavilion angles. I feel CZ might be quite nice too, but suggest lower pavilion angles (say-37 degrees) for it as well. The design as listed here should work well with quartz, beryl, tourmaline, topaz, etc.


Index of Gem Designs

Perfect Transfer Index

Table of Contents


© Bob's Rock Shop Bob Keller