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Gem faceting

Double E

Brilliant_Rock
Joined
Jun 23, 2018
Messages
944
Haven’t been posting for quite a while, I have finally started learning basic gem faceting.

It went quite smoothly, of course with a number of beginner mistakes, but enjoyable. After finishing my first cut stone of simple design in the first lesson, I can now say that I like it after trying. Hopefully to cut one or two more of different designs before this workshop ends. And it’s also accessible for me to continue after that by renting cutting machines.

Feels good to develop a new hobby. And I am wondering where I can buy and get roughs suitable for beginners?
 

Double E

Brilliant_Rock
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Jun 23, 2018
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944
Are you cutting the crown first? You may find it easier to cut the pavilion first.

Yes, Gene, I simply followed the steps taught by the teacher as a zero experience student. How does it make it easier cutting the pavilion first? Definitely want to gain more understanding while practicing skills.
 

Double E

Brilliant_Rock
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Jun 23, 2018
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If you run out of stone, it's better to make compromises on the crown than the pavilion. Lowering a crown will have much less effect on the performance of the stone, than cutting the pavilion too shallow. Most, not all, "precision" cutters will cut the pavilion first.

Got it! Thx very much for the advice, much appreciated:)
 

Double E

Brilliant_Rock
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Jun 23, 2018
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And I am cutting a triangular design today. I am not able to finish it, because I spent too much time to cut the six flats of girdle. I started with a preformed stone, however it’s not a triangle with even sides. And the fact that I began with the girdle badly, the meet points of this stone are gonna worse than the first one. I will finish the pavilion and the whole stone in next lesson.
97FA8C4F-FD56-48D2-A3AD-0D53E235397F.jpeg
 

Double E

Brilliant_Rock
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Jun 23, 2018
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944
And I talked with the instructor about first to cut pavilion or crown. She said mature and experienced cutters usually cut pavilion first, but did advise beginners to do the opposite. They thought it’s easier to do adjustment on pavilion, what I got from her words is more material to cut out for any necessary changes needed. They do tend to avoid changes made in the crown, I am not sure it’s because Asia market emphasise so much on crown and table, or they hold a different view on performance though.
 

PrecisionGem

Brilliant_Rock
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Jul 27, 2004
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What's kind of strange is she has you cutting a design that was made for meet point cutting. In almost all meet point designs, the pavilion is cut first, and the pavilion then creates the outline for the girdle. If the pavilion is cut correctly, then the crown falls into place and both are cut correctly. Notice the first step in the instructions is cutting the pavilion.

Get your self a copy of the software GemCutStudio. I think using this will really help you as you can use the "cutting assistant" feature to replay each facet being cut. This will then show you how to cut to the meet points to form the stone.
 

PrecisionGem

Brilliant_Rock
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Freak out your instructor and cut the pavilion first. I would cut 2 then the girdle then 3. Transfer and cut A, B, C.

If you have the material, you cut the pavilion tier 2 to a center point. Now when you cut the girdle, you will create a round stone, as you can cut to level line. Pretty much all these designs you are getting online are created with the pavilion facets creating the outline of the girdle.
 
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Double E

Brilliant_Rock
Joined
Jun 23, 2018
Messages
944
Freak out your instructor and cut the pavilion first. I would cut 2 then the girdle then 3. Transfer and cut A, B, C.

If you have the material, you cut the pavilion tier 2 to a center point. Now when you cut the girdle, you will create a round stone, as you can cut to level line. Pretty much all these designs you are getting online are created with the pavilion facets creating the outline of the girdle.

I had your words in mind Gene. I will still be renting their equipment to cut after the class, and it will be my “free” time from there. I will use the pavilion first method, and want to keep practicing. Please, everyone, do keep giving me advice.
 

Double E

Brilliant_Rock
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Jun 23, 2018
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944
Do they use cone dops, and are you using a transfer fixture to move the stone from one dop to another?

They have both cone and flat ones, and was usually given flat one and they attach the gem to the sop for me so far.

This is another thing I need to consult. I only tried the “cool gel” but the stone fall out twice, it looked like I put not enough gel to attach. I have yet to try shellac, that I usually see from western cutters?
EE7F8C9F-970A-4892-812C-1A119DCAE0AC.jpeg F3DD2770-835E-453F-ABB7-84922F38D07B.jpeg B3F2BA0D-E464-44BE-91C1-0565C201A987.jpeg
 

Double E

Brilliant_Rock
Joined
Jun 23, 2018
Messages
944
Do they use cone dops, and are you using a transfer fixture to move the stone from one dop to another?

In regards to transferring the stone from one dop to another, like at the time when we finish the pavilion and move to the crown, I asked and was told I can use the device that I pointed below. I haven’t tried yet and wanna know is this the only way.

698F6B49-CCAF-470D-8ACC-BB612DD1B0D0.jpeg

In fact I had a question from the beginning about how to make sure the index of the stone is still correct after moving between dops, and I was like trying to judge it visually first, then give a very short polish on the lap and then fine tune placement of the dop to achieve that accuracy. Seems a bit time consuming and prone to human error.
 

PrecisionGem

Brilliant_Rock
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The basic principle of how you are cutting compared to western cutting is the same, but the equipment is different. In the east, speed is a prime concern, and the west accuracy and precision is the main concern.

The device you have shown two posts up, it's blue, is similar to our transfer fixtures.

Here's a photo of a stone going into the transfer fixture.

Screenshot 2023-09-08 at 10.25.15 AM.png

The first dop, on the top will be the crown. I use wax to attache the stone to this top. When I transfer it into the bottom dop with the cone, I use epoxy. Then a little heat to the top dop and the stone is released. Both dops hove keys to the index is fixed between them.

Have a look at this page on my site showing my cutting workshop.

 

Double E

Brilliant_Rock
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Jun 23, 2018
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944
Btw, I’ve downloaded the gemcutstudio. Will take a look at how it works this weekend as I don’t need to work.
 

Double E

Brilliant_Rock
Joined
Jun 23, 2018
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944
While I may mainly buy some lab stones for cutting, Is zircon good as a practising stone when it comes to natural gems? Considering it’s properties. And there seems to be good deals online sometimes for zircon roughs.
 

MarcoV

Rough_Rock
Joined
Jun 24, 2021
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Zircon would be OK-ish. I'd suggest beryl or garnet, tho. They probably are the easiest to cut and polish.

As for synthetics, YAG would probably be your best option in terms of ease of cutting/polishing. And they make beautiful gems too! I won't advise lab corundum as a "first-ish" stone. You want to get materials as easy as possible to cut and polish, to focus on -ehm- polishing your technique. Differential hardness, chippy materials, difficult to polish materials, etc. can wait for now.
(Unfortunately, also quartz is not the easiest stone to start with... )
 

PrecisionGem

Brilliant_Rock
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A lot of people start with quartz, as it's pretty inexpensive, but I find it one of the more difficult stones to polish. Doesn't polish with diamond, so you will need other laps to polish. Personally, I find corundum the easiest stone to polish. Tourmaline can be easy to work with as can garnet, but sometimes you get a facet on garnets that tinny pieces come away, get stuck on the lap and scratch.
Zircon is a little trick as it's soft in one direction and hard in the other. You will tend to over cut the softer orientation.
 
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