Barion Old Mine by Bob Keller

Barion Old Mine Planviews

GemCad Ray Traces for RI = 1.54
Random Model Cosine Model 64.9 ISO Model 70.00
GemCad Ray Traces for RI = 1.72
Random Model Cosine Model 74.2 ISO Model 83.4

Barion Old Mine by Bob Keller 11-98
Angles for R.I. = 1.5473 facets + 12 facets on girdle = 85
4-fold, mirror-image symmetry96 index
L/W = 1.000 T/W = 0.549 U/W = 0.549 P/W = 0.511 C/W = 0.178
Vol./W^3 = 0.288 Brightness at 0° tilt
RI = 1.54: COS = 64.9 ISO = 70.0
RI = 1.72: COS = 74.2 ISO = 83.4

m42.00°96-04-08-12-16-20-24-28-32-36-40-44-48-52-56-60-64-68-72-76-80-84-88-92Cut to permanent center point
g190.00°12-36-60-84Establish size, lower girdle line
g290.00°02-22-26-46-50-70-74-94Meet g1.m.m
b175.25°02-22-26-46-50-70-74-94Meet g1.m.m.g2
b270.39°96-24-48-72 Meet g2.b1.g2 and b1.m.m
s145.00°02-22-26-46-50-70-74-94Match g2, establish upper girdle line
s246.00°12-36-60-84Level girdle meet g2.s1.g1
s335.00°02-22-26-46-50-70-74-94Match s1, leave face width s1 = .141W
s435.60°12-36-60-84Meet s1.s3.s2
s520.00°02-22-26-46-50-70-74-94Meet s3.s4.s3
d39.63°96-24-48-72Cut short of meeting g2 and s5
t0.00°TableCut level table, leave face width s5 = .027W

Download PDF format printer friendly cutting instructions: [ Download Icon Barion Old Mine Printer Icon ]

Download the GemCad format design file: [ Download Icon barion_old_mine.gem ]

Barion Old Mine Cutting Remarks

I designed this cut for a squarish piece of amethyst that had a nice color but was a little on the light side in terms of saturation. I wanted something that would be relatively easy and quick to cut, and which would have the effect of making the material appear to be more deeply color saturated than it really was, but still have a good play of light.

My initial idea for the stone was to use barion facets to mate the pavilion to a 24-sided, cushion shaped crown with 3 or 4 tiers of step cuts around. However, a desire to cut something quicker prevailed, and since I've always thought the old mine shape was attractive, I decided to try it. I also wanted to be able to mount the stone in a standard 4-prong finding, hence the cut corners. I'd guestimated a little larger stone than 14mm across the corners, but after I got finished cutting away a late discovered and deceptively deep flaw, 14mm it was.

The pavilion-up image at right gives an idea of the actual color saturation of the rough. I got the color deepening effect I needed, and I was also pleased with the dispersion - the stone shows some nice red and violet flashes.

This design is pretty straight forward to cut. After cutting the pavilion mains, the g1 girdle facets are cut to an equal depth, determining the size of the stone and establishing a level girdle. The b2 facets will cut in very quickly, so exercise care with them. I cut the b2 facets on my stone by hand wiping it across a stationary 1200 lap. They could be skipped if you're so inclined. If you leave them out, the b1 barion moon facets will form a scalloped shape, which just looks a little less finished to my eye.

Note and keep in mind that the g1 corner girdle facets are cut at a different elevation than the g2 girdle facets, and that the s2 and s4 corner crown facets are cut at a different angle and elevation than their s1 and s3 counterparts.

The crown is an easily embellished step cut. It's important to establish a level girdle after you transfer, or you'll wind up cheating yourself blind trying to make the step facets parallel and get their junctions to meet.

If you cut a Barion Old Mine, let me know what you've cut it in and your results. Enjoy!

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Bob Keller