“3LD” Triangle: Faceting Design Diagram

Detailed information and guide for Faceting Design Diagrams. This facet design is called a " "3LD" Triangle". This design is a good triangle to cut.


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

Jeff R. Graham

The late Jeff Graham was a prolific faceter, creator of many original faceting designs, and the author of several highly-regarded instructional faceting books such as Gram Faceting Designs.

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