IGS Background

Line Point Triangle: Faceting Design Diagram


Helpful tips and guide on Faceting Designs. A Faceting Design Diagram by Jeff R. Graham that presents various cuts, this one is called "Line Point Triangle"

By Jeff R. Graham, updated on

Spinel (Red, Pink, Lavender, Green, Blue, Orange, Violet)

Line Point Triangle (SPINEL1.JRG)
By Jeff R. Graham
Copyright 1995
87.2% Light Return
Angles for R.I. = 1.71
31 facets + 12 facets on girdle = 43
3-fold, mirror-image symmetry
96 index
L/W = 1.104 T/W = 0.496 T/L = 0.449
P/W = 0.481 C/W = 0.188
H/W = (P+C)/W+0.02 = 0.689
P/H = 0.698 C/H = 0.273
Vol./W^3 = 0.211

Addition # 2 - This triangle cuts easily and makes a nice stone in about any type of material, 1/2-4cts. I like it in light colored Garnet and Sapphire. Cut in refractive indexes 1.71 to 2.14 with no changes. This design is deceptive, it is really quite nice.


Random - Cosine - ISO

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!