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| Rainbow - designed by Jeff R. Graham jeff@faceters.com ©2005 | |
|---|---|
| Angles for R.I. = 1.62 | 73 facets + 16 facets on girdle = 89 |
| 2-fold, mirror-image symmetry | 96 index |
|
L/W = 1.340 T/W = 0.865 T/L = 0.646 P/W = 0.577 C/W = 0.145 |
H/W = (P+C)/W+0.02 = 0.742 P/H = 0.777 C/H = 0.196 |
| Vol./W^3 = 0.369 | Brightness at 0 degrees tilt for R.I. = 1.62 85.3% Light Return |
| Pavilion | |||
|---|---|---|---|
| P1 | 42.00 |
03-09-15-21-27-33-39-45 |
Cut to center point. (Cut a 1.34 pre-form) |
| P2(G) | 90.00 | 02-46-50-94 | Cut to meet P1. |
| P3(G) | 90.00 | 06-42-54-90 | Cut to meet P1. |
| P4(G) | 90.00 | 10-38-58-86 | Cut to meet P1. |
| P5(G) | 90.00 | 19-29-67-77 | Cut to meet P1. |
| P6 | 62.00 | 19-29-67-77 | Cut to meet P1,P5(G). |
| P7 | 65.23 | 10-38-58-86 | Cut to meet P1,P4(G). |
| P8 | 66.73 | 06-42-54-90 | Cut to meet P1,P3(G). |
| P9 | 67.44 | 02-46-50-94 | Cut to meet P1, P2(G). |
| P10 | 40.22 | 96-48 | Cut to center point, P9. |
| P11 | 40.50 | 12-36-60-84 | Cut to meet P7,P8, center point. |
| P12 | 40.85 | 24-72 | Cut to meet P6, center point. |
| Crown | |||
|---|---|---|---|
| C1 | 46.00 |
02-46-50-94 |
Cut to meet girdle. |
| C2 | 46.00 | 06-42-54-90 | Cut to meet girdle. |
| C3 | 45.65 | 10-38-58-86 | Cut to meet girdle. |
| C4 | 44.69 | 19-29-67-77 | Cut to meet girdle. |
| C5 | 39.88 | 96-48 | Cut to meet girdle. |
| C6 | 39.44 | 08-40-56-88 | Cut to meet girdle. |
| C7 | 31.49 | 24-72 | Cut to meet girdle. |
| C8 | 14.22 | 16-32-64-80 | Cut to meet C3,C4. |
| C9 | 24.92 | 04-44-52-92 | Cut to meet C1,C2. |
| T | 0.00 | Table | Cut to meet C5-C9 |
Rainbow - Cutting Remarks
Shown at left is a 13.1mm x 17.8mm x 10.5mm deep ~ 18.53 carat Rainbow cut from flawless Rose Malaya Garnet by Jeff Graham.
This is an updated version of my original "Rainbow" design.
The original "Rainbow" has always been a very popular cut with people. But it can be difficult to cut, particularly for an inexperienced cutter. It is the design I hear from people that they have the most trouble with.
So I decided to re-work the original and make it better and easier to cut for low milage cutter. This design is still not easy and I do not especially recommend it for a new cutter. But it's definitely easier than the original.
This version is better performing in lower refractive index materials and I particularly set it up for 1.62, Tourmaline and Topaz. Cut in refractive indexes 1.62 to 2.14 with no changes. For Quartz add .3 degrees to all the pavilion tiers (40.5 degrees).
It is very easy to end up with the wrong L/W on Omni point barions so a preform of the correct L/W is always helpful.
Note: If your breaks look like the rocky Mountains, check your L/W, it is probably off one way or another.
I bought this Garnet as a native cut and it was really awful... I needed to design something that would give me a decent weight return and still get some life into this huge red Garnet. I decided that I needed a brilliant Pavilion, even if the rough loss was going to be higher and it sure was.
Enjoy cutting your "Rainbow"... Drop me an email to let me know your results and what you've cut, or feel free to inquire if you have any questions or need some help regarding this design.
Random - Cosine - ISO
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