IGS Background

Inca Dome: Faceting Design Diagram


Successful tips, details and guide on Faceting Designs. Faceting Design Diagram by Jeff R. Graham that presents various cuts, this one is called "Inca Dome"

By Jeff R. Graham, updated on

Tourmaline (Achroite, Dravite, Rubellite, Indicolite, Verdelite, Siberite)

Inca Dome Jeff Graham Facet Design 1Inca Dome Jeff Graham Facet Design 2

Inca Dome (DOME21.JRG)
By Jeff R. Graham
Copyright 2007
85.6% Light Return
Angles for R.I. = 1.62
81 facets + 16 facets on girdle = 97
8-fold, mirror-image symmetry
96 index
L/W = 1.000 T/W = 0.277 T/L = 0.277 P/W = 0.405 C/W = 0.319
H/W = (P+C)/W+0.02 = 0.744 P/H = 0.544 C/H = 0.429
Vol./W^3 = 0.247

PAVILION

CROWN

Addition # 13 - Cut in refractive indexes 1.62 to 2.14 with no changes. This is nice and works well in light to mediumly saturated materials. I like it in mint and fancy colored Garnets as well.

Inca Dome Jeff Graham Facet Design 3

Detailed faceting instructions by Jeff Graham available at The Rock Peddler

Never Stop Learning

When you join the IGS community, you get trusted diamond & gemstone information when you need it.

Become a Member

Get Gemology Insights

Get started with the International Gem Society’s free guide to gemstone identification. Join our weekly newsletter & get a free copy of the Gem ID Checklist!