Subject: Faceting Academy: Tighten Your Girdle & Witch Angles

TIGHTEN YOUR GIRDLES

The newest additions to the Official Facetron Video series are more ways to tighten your girdles by "Sighting the Rifle".

I released a video a couple of weeks ago about how to do this with a tool you can make yourself. It's on the site right now here:


On Tuesday, I'm releasing the third video on "Sighting the Rifle (zeroing the cheater)" - using a $39 tool you can buy from Amazon - and the link to the tool - a great stocking-stuffer for any faceter - next to the video. That one is:

Chapter 9 c: Calibrating the Cheater
(using a $30 electronic tool)

I'm going to be releasing more videos right up to Christmas, so make sure you stay tuned!
NEW FAVE PRE-POLISH LAP

Speaking of tools - and stocking-stuffers for faceters, I've got a new favorite pre-polishing lap.

In a pre-polishing lap, we're always looking for a couple of things - including a consistent smooth finish that's easy to polish from - and also something that removes material quickly so you can get past the damage left by cutting. We also want the thing to stay smooth and sharp...

For a while, I've recommended the resin-bonded diamond laps because they were relatively trouble-free and flat. But, they aren't very fast; they're prone to damage (or orange-peeling harder stones); and they glaze and get slow.

I've just tested the Zinc+ by Gearloose - a laminated Zinc lap that you charge with your own pre-polish - something like my Voodoo 2k or 3k pre-polish, because handling loose diamond is a pain - and a contamination risk.

Here's a photo of a Spessartite garnet pavilion with a finish left by 2k Voodoo:

Spessartite garnet pre-polished
The finish was really nice to polish from - with just a few strokes required on the Diamatrix charged with 50k Voodoo.

However, it moved SO fast that I'm going to step it down to 3k Voodoo on the next stone.

The lap is incredibly flat - with my Facetron indicator needle barely moving. It's very smooth, and super-easy to use: Just charge per usual, and the more you use it the faster it gets. A little refresher once in a while - or a drop of some light oil like 3-in-1, and you're going like a rocket.

One of the best things is you can keep it working rocket-fast with the tiniest of Voodoo re-charges, and it's not messy at all.

You can order my new favorite pre-polishing lap here:


WITCH ANGLES?

This is a response to the mail bag:

Question:

Which chart is recommended for pavilion angles vs refractive index?

Answer:

Pavilion angles are a function of refractive index, but somewhat dependent on design. Most angles charts are supposing the Standard Round Brilliant, therefore of very limited use.

If you are cutting SRBs, use a standard chart based on RI.

If you are cutting anything else, you need to use ray-tracing to determine angles for the material and design.

For example:

I did a side-by-side ray-tracing of an SRB and my "Indigo" OMNI 1.33 oval. In one test, I set the culet angle to 43 and the other to 41 (on both designs). I let GemRAY optimize the crowns, but it only shifted by 1 degree on both designs, so that didn't make much difference.

With 43 degree culet angles, the COS table brightness scores were:

SRB = 54
OMNI = 27

With 41 degree culet angles, the COS table brightness scores were:

SRB = 37
OMNI = 45

These scores are a good reflection of the objective overall appearance of the ray-tracing.

If a person had used a chart that said to use 43 degree culet angles, they would have done good with the SRB - but not very good with the more complex OMNI - which at 43 degrees throws some significant extinction / head-shadow.

There's a detailed and easy-to-follow section on this stuff in my upcoming book, due out early in the New Year. Stay tuned for more details - and more sneak peeks.

TRIBUTE TO A MASTER

It's been a rough week in the faceting community, with the loss of our friend Stephen Kotlowski. He was known for a sense of humor in addition to being one of the true masters of our time - a giant of this craft.

Words are feeble things to convey the loss in industry, in artistic, and in personal terms.

The best I can do is to say it's beautiful to see the ongoing publication of photos of both Stephen's always-smiling face - and his work - and the expanding interest of upcoming artists trying to follow where Stephen lead.

Farewell to a master known for his kindness as much as for his considerable prowess at the lap. In his honor, may both of those things proliferate in this art.


HAPPY HALLOWEEN
FACETING DESIGN


I felt it was time for some PLAYFULNESS in design - and cutting, and I wanted to do something fun for Halloween. A jack-o-lantern came to mind, and the triangle eyes reminded me of one of my favorite designs by one of my favorite designers, the late Fred Van Sant - his FVS-233. So, the design I'm going to share is a derivative of that one.

Because this was a much-needed playful departure from my over-worked schedule, I'm calling it "No Dull Boy".

Here's a photo of the test cut in Nigerian Spessartite Garnet at 7.1mm, and weighing 1.62 carats:
You'll need a higher-RI material for the pavilion angles to work. You'll want to leave the crown un-polished (I recommend a worn 600 metal bond or a 325 resin bond lap).

And, you want to pre-polish the shiny facets in shy of their finished levels. I put the eyes and nose in entirely with 50k diamond on a Diamatrix lap, so be very careful.



I hope you enjoy cutting it. If you do - and share a nice photo, I may publish it next month. And, if I do, I may send you a stocking-stuffer...

Stay tuned for more free designs, training videos, and other news!


Meantime, you and yours have a happy and playful holiday season.


John Bailey,
Founder, Faceting Academy
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John Bailey, 1010 Main St, Klamath Falls, Oregon 97601, United States
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