Posted at 3:00 • 6 Dec • Nick Alexander • Gemstone Artist
How to Polish a Gemstone Carving
Polishing a Gemstone Carving with a Flex Shaft or Dremel
Gemstone carving is made up of three major steps. Starting with the grinding stage, then moving into a sanding process, and finishing with a polishing process. Each of these steps are important to understand and master in order to produce a high-quality finished gemstone carving. In this article we are going to discuss everything you will need to know during the polishing process of a gemstone carving.
During the polishing process you will run into many different issues. Every material you cut will polish different and it is important to remember that polishing is an art in itself. You have to spend time on the stones you are cutting in order to make them perfect. Learning how to polish a gemstone carving happens over the coarse of many stones.
We will discuss some of the major issues that happen when polishing and what supplies best work. Cutting Edge Supply has a wide range of supplies that are specifically altered for gemstone carving. We have spent many years trying different tools and manufacturers to find what works best. So take a look at some of the basic items that are listed below for polishing. If you have never polished a gemstone carving then these are great starters. The Polishing Kit will have everything you need. If you have some experience in polishing then go under the tab Polishing Supplies to find more tools that might help you!
Sunstone Carving by Darryl Alexander
In Order to Start...
This article will go over everything you need to know in order to begin polishing. In order to start polishing a gemstone carving you need to have sanded it to a #600-#1200 Grit. You want to ensure that all of your lines are clean and crisp. There is no chatter lines from previous grinding on any of your gemstone carving. Examine the stone with a 10x loupe and look for any chipping or missed areas. If you see any of this, then go back and fix it before you start finishing. By doing this you will set yourself up for a high-quality polish without having to work too hard.
If you need more information on sanding a gemstone carving then check out our page named "Sanding a Gemstone Carving with a Flex Shaft or Dremel." Don't forget to always wear the proper safety equipment. For more info on safety click here.
Take your time. There is no rush to be good or renowned.
The Starting Steps
To begin polishing I start with a #600 grit diamond syringe or compound. I use this grit so that I can work out anything that I missed from sanding. I work the entire gemstone with a hard surface to smooth out all my lines. A #600 grit compound will slightly cut gemstone if you are using it with the right medium. Us the compound with harder materials if you are trying to cut. I always begin with a hard surface so that I do not spend too much time later with a softer material, like a bristle brush.
I personally like a hard felt wheel if I am going to start my #600 process. Hard felt wheels hold compound very nicely and will smooth out all the imperfections left from the sanding process. Cutting Edge Supply's 50pc Hard Felt Set is great for giving you a wide range of different shapes and sizes to pick from. Choose what shapes will work best for your carving. Don't be afraid to use a few different shapes in order to get into all crevasses of your carving.
While you are working the stone with this #600 grit you should see the surface of the carving become more consistent. Make sure to hit every spot! If you run into a spot where a hard felt wheel isn't cutting enough, then use a material like wood, copper, or phenolic. These materials are slightly harder and will provide more cutting action.
After you have worked the entire gemstone with a harder surface then use a bristle brush. Bristle Brushes, for the most part, will always give you the best finish. It is important to finish the gemstone to the best of your ability in each grit you decide to work. That way when you move to your next grit, it will be easier!
When using the bristle brushes with a #600 grit compound you are trying to create an even, consistent, and smooth surface. The bristle brush can create an even matte texture across the entire gemstone carving if used correctly. The spots that don't consistently match the rest of the carving usually need to be finished better.
The majority of my polishing time is spent using a #600 grit. It is without a doubt the most crucial part while polishing. If you have a good #600 grit then everything else will be a breeze!
After finishing with the #600 grit I move on to a pre-polish. During the pre-polishing stage you will be repeating many of the same steps that you did during the #600 grit process. The same process will be used throughout all of the girts.
I begin with hard felt wheels and start to work the surface of the stone. I charge my felt wheels with a #1200 grit diamond compound. In the carousel you will see a gem polishing compound. This is my personal favorite to use because of its high concentration of diamond and long lasting life.
This time when you are using your felt wheels you should see the surface of the stone start to glaze, or polish. This is good! That means the paste is doing its job!
During pre-polishing you might run into some trouble with imperfections showing up. It tends to do this because now that it is starting to polish, you can see exactly what you are doing and what you have missed. Along with the gem polishing compound, you will find some of my favorite tools to use when I am in need of a quick fix while polishing.
1: Rubber Bristle Brush Set:
This set is full of small rubber wheels that are perfect for cleaning up small spots on your carving quickly, and easily. It has 3 different grits to use depending on how bad the imperfection is. Then you can go all the way back up to a polish with these and don't have to redo the #600 grit.
These Rubber v-wheels are prefect when you need to clean up a deep line or get into a spot with precision. These wheels also come in a wide range of grits however if you are at this point of polishing then I would suggest the grits fine or super fine. These two grits will work out even the deepest of scratches and bring it back to a polish so that you can resume your cutting.
3: Diamond Adhesive Pressure Pads:
These diamond pressure pads are great if there is a large section of your carving that is choppy or inconsistent. A #1200 grit pad will smooth out your surface and get rid of any chipping that may have shown up.
Once you have worked out any final issues with your carving and gotten it to a nice pre-polish with felt or wood, then you can move to bristle brushes.
As I mention before, try to always end with bristle brushes in each stage. This will give you the most consistent finish and the highest finish. You are aiming to get what looks like a final polish. The closer you can get the stone to a polish in this stage, the more glassy it will look when you are done. The #1200 grit diamond compound I suggested should almost polish if used correctly.
The Final Polish
If the pre-polish is done correctly then the last step to polishing a gemstone is very easy. Normally a bristle brush will do the trick for a final polish. I use the final grit in Cutting Edge Supply's Gem Polishing Compound, however any diamond paste with #3000+ will work. Certain materials, like agate and onyx, will need a grit that is #8000+.
When you are charging your bristle brush, don't use very much compound to begin. A slow speed and heavy pressure will make the diamond cut more. By using heavy pressure and a slow speed when you cut it will smooth out the surface faster and the bristles will conform to your stone more. With this last step it is all about getting the highest polish you possibly can.
Therefore, when you are done working the stone with a slow speed and heavy pressure, move to using a high speed and light pressure. This will give you the best finish. A faster speed makes the diamond compound brush up against the stone rather than dig into the stone.
Extra Tips and Info
Here is some extra information on polishing gemstones:
1: Softer Materials Can Be Polished With Zam
For materials that have a hardness of 6 or lower on the Moh's Hardness Scale, you can polish by using Zam/Fabulustre Buffing Compound. You will only need to sand the gemstone to a #600 grit before buffing. This allows for a very fast finishing process. (Materials like: Turquoise, Charoite, Shattakite, Larimar, etc.)
2. The Cabbing Machine Can Come in Very Handy.
When finishing a gemstone I always suggest using a cabbing machine wherever is possible. The cabbing machine will give you the smoothest and best finish when it comes to large flats. So if there are any large spots that can be reached with a cabbing wheel then use it! Cabbing machines will also minimize any under-cutting if you're working where this shows up.
3. Undercutting is Reduced When You Use Hard Materials
When you use a soft tool to polish like a bristle brush, it allows for softer parts of the material to be cut away quicker than the hard parts.
So if you are cutting a material that is inconsistent with its hardness, then it is best to stick to materials like wood, copper, and diamond pressure pads in order to finish the gemstone. The harder the bur is then the most consistent it will cut. Pressure pads work well because they do not cut deeper in certain spots, they cut smooth.
Use a cabbing machine as much as possible. It will be the easiest way to finish the carving and not have undercutting.
Check Out Our Other Articles
I hope this article will help you with your future cutting! Check out our other articles to find more information on gemstone cutting!
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