Faceting Design Diagram: “3LD” Triangle – Spinel – Red, Pink, Lavender, Green, Blue, Orange, Violet


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

“3LD” Triangle (SPINEL.JRG)
By Jeff R. Graham
Copyright 1995
79.2% Light Return
Angles for R.I. = 1.71
52 facets + 12 facets on girdle = 64
3-fold, mirror-image symmetry
96 index
L/W = 1.009 T/W = 0.472 T/L = 0.468
P/W = 0.377 C/W = 0.190
H/W = (P+C)/W+0.02 = 0.587
P/H = 0.643 C/H = 0.323
Vol./W^3 = 0.189

Addition # 3 – Here is a good triangle to cut, watch the apex at P3,P5, this establishes the P6(G) girdle facets. The P4 & P7 facets may have to be rubbed in, especially on a small stone, 1-12cts any good material. Cut in refractive indexes 1.71 to 2.14 with no changes.


Random – Cosine – ISO

Detailed faceting instructions by Jeff Graham available at The Rock Peddler

Gram Faceting Archive of Information
This edited version of an article by the late Jeff Graham is part of a special archived informational series from Gram Faceting. Used with permission.