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Faceting lap issues

Hi Everyone
I really need some help. I’m an amateur facetor with a Facetron I’ve had for a number of years. I’ve recently bought a new set of Diamond Tech laps, replacing same but the old ones are so worn. I’ve got 220, 600, 1200 & 1800 grit. I’m having big problems with scratches on the facets especially with the finer grits. I clean and wash everything before putting a finer lap on the machine, base plate, lap, stone, hands, even the lock nut, but still I get scratches. Sometimes it’s fine, then **** more appear. Any tips or ideas please.

Hi Jamiefort,

Form the info you provided you are well set. On my side I am using those lap grits for cutting and fine cutting.
For polishing I am using flat laps with 5000, 12000 and 50000 grits pastes. I am amateur too. I invested in three aluminium flat laps dedicated to each polishing step. I am getting scratchless polishs that ways.
Hernst, T., 2014 Amateur Gemstone Faceting vol 1., 400p. Would provide you much more clues and solutions to you polishing issues.

All the best,


1 Like

Hello. I too am an amateur hobby facetor. I started cutting mid-December 2019 (pretty much exactly 1 year ago).
I too have had some issues with older laps that appeared to be damaged or contaminated somehow. I have since move to using Topper Laps which I have had No Issues with. But my biggest problem was with Polishing. I have 260, 600, 1200 and 3000 grit Topper Laps. I pre-polish almost everything with the 3000. I have only ever used my Copper lap for prepolishing a few times (after giving it a new surface).

The laps I started with for pre-polishing and final polishing all started scratching my stones. It’s super frustrating. So I did two things that have made a world of difference for me.

  1. I got my Tin Lap re-turned at a machine shop … to ensure a new, clean, uncontaminated surface. I use it almost specifically for polishing Corundum (lab-made Ruby/Sapphire), CZ and sometimes use it to polish Garnets or even stubborn Peridot. I use 60,000 grit Battstik on it.
    I resurfaced the copper lap on my own and use it for 8000 grit prepolishing.

  2. I purchased a “Matrix” polishing lap (Ceramic) … I use it specifically for Oxide Polishing (it can be used for diamond OR oxides but not both). I use the Aluminum and Super Cerium Oxide Battstiks on it along with “Snake Fluid”.
    To be honest, I’ve had pretty good luck with a Corian lap as well. I know people are going to laugh at my reply but I survive on a Disability Pension so I have to work with what I have and a very limited budget. I’ve been pretty lucky so far and am super-satisfied with Matrix Lap. I couldn’t afford anything better if I wanted to. So it has paid off very well for me.

Between the two changes/investments, I have not had ANY more issues with scratching during the polishing process, making me a happy camper ! :slight_smile:

So the only advice I can suggest is either New Laps (including Toppers) if you are getting bad scratches while Cutting OR find a way to decontaminate your current laps. But I understand it’s hard to decontaminate a diamond lap if you don’t know where the contamination is. One can spend a significant amount of time with a loupe trying to find the source of scratches and there’s no guarantee you will see/find anything. Even if you can see the source, getting it out can be another problem. I guess the only other thing would be to run the lap in reverse and run some “material” (CZ or Corundum ?) over the entire surface with hopes that it might back-out the contaminate.


Im also a self taught amateur and found reading material on subsurface damage caused by laps too course leaving fractured crystal structure below the surface that shows up in the fine polishing as scratches.

Some material should be preformed with nothing more than 800 at the start or even 3000.

Believe it or not I’ve found CDs or DVDs can give excellent results in polishing stages - impossible to polish girdles on my 8 “ Jersey but again - never use a 260 - 600 unless planning to remove a sufficient amount of material before getting to polish grit by coming through lots of 3000 - 8000.

I have copper - Corian - and Bat laps and tried them all but DVDs splashed with Acetone on the spin to rough up the surface applied with a folded soaked paper towel until it turns white then it’s ready to load with Diamond grit using wd40 or musical instrument oil but CDs don’t like alcohol/Olive oil - the alcohol seems to cause pitting.

This got blended into my post somehow - my comment ends here.

I am using adamas faceting lap. Works the treat for me. 3000 diamond on batlap for pre polish. Could not be happier with the result.
I also clean my lap with lava soap after every use and spin it dry.
For deap clean of lap I use cerium sticks.

Hey Everyone. Thanks so much for all your replies and so much to look through and try out, I really appreciate your comments and I can stop pulling my hair out!!
I’d love to know a bit more about polishing laps, never heard of Aluminium ones. I’ve got an old tin/lead one that might need skimming. Is that actually possible? Any thoughts on tin laps and copper laps.
I’ve got some Cerium oxide I use for vibro-polishing, could I use that on my faceting machine? I guess it will need a dedicated lap too.
Loved the comment about reversing the lap direction to clear the rubbish out. Is this the only way to ‘dress’ a lap like these Diamond Tech chaps or are their others? Is that what a Cerium stick does?
How do I use lava soap? Just on a cloth while washing the laps or is there a better technique?
Once again, many thanks for your help.

I just put the soap to the spinning lap and rinse it while spinning and always spin it dry before take it off. That is on my cintered wheel. You can resurface your tin lap and recharge it with your favorite compound.
There is many ways to skin a cat and it’s is a lot of equipment to use. I like to keep it simple. I rugh my stone in with 300 or 600 grit. Then I use my sintered wheel to cut all facets. 3000 on a batt lap seam to work with everything for me then a polish lap. I use the backside of my batt for 60000 and a darkside for different oxides. Now I can not repeat angels with precision as I use a platform
So that is plenty good for me. Maybe not good enough for competition cutting , then another approach would be better.

That’s really great advice again. Many thanks.

I hear you! I also am a non-professional, but have many, many years, on and off, of experiencing the frustration everyone seems to keep reliving.
What have I done? The complexity, I think, is because of the lack of reasonable communication and study. It is an issue that authors would rather not get into and don’t really offer help, Sure aggregation can be a cause, but what to do about it. For the last 6 months I have experienced virtually none of the horrors you all speak about. To my surprise, a solutions is not complicated.
Yes, of course be careful and wash disks and hands often. When you have scratches on your polishing laps with Cerium Oxide or Alimina A, try this;
If the scratching is clearly a single speck, spin the disk and any speed and apply a pad of fine steel wool with moderate pressure to the wet surface for about 15 seconds. Run water if you wish. Unmount the disc and wash thoroughly. The fleck should be gone. If not repeat. It has not failed for me, 4 times. out of more the 60 stones.
If the scratches are multiple and not severe try this. During cleaning of the disk with water, dry it with a piece of LINEN toweling. It has to be linen, cotton won’t do. When you are done, you will find that the cloth has swaths of black on it.and the disk has a burnished sheen. I suspect this black is an oxide of lead which remains with routine washing. Over time the black mess reduces to almost nothing. Since doing this I have had no scratches, whereas before it was almost routine that “scratching happens”.
Now to diamond disks 600 to 3,000. Once you are sure that there are no REAL defects on the disk, and that can be a problem, as I have found to my dismay, (that is, flecks of contaminating oversized diamond embedded on he surface) I did something that is probably heresy! I had been using distilled water with a small amount of surfactant. The scratches strongly suggested aggregation of rock dust producing multiple shallow scratches, but scratches nonetheless. OK I can understand that! But what to do?? Books were and are no help. So out of the box----STOP using water. On each of the 4 problem disks I used WD-40 instead, no water. I suspect other penetrating oils will do. I started with an old 600 disk that was a trouble maker as well as poor cutter. A liberal spray of WD-40 applied as needed, was applied while spinning at low speed and distributed with a clean finger. I could not believe what happened. This old dull disk started cutting beautifully! And as I moved on to the next steps, there were no scratches. Same with the 1,200. Since doing this step the whole process has been far less irritating. What is happening? The oil prevents aggregation and the centrifugal forces allow the rock flour to spin to the periphery and out of play. If you apply a spurt of oil to the inner aspect, at medium speed, you can see the white ring of dust moving to the edge.
Now the 3,000 diamond disk. I have 3 and each has been a problem from the get-go. Small shallow scratches that could be polished out, with patience. The WD-40 trick helped but not totally. I eventually had to use only scratch-free radii with oil and could get away with it.
As for contaminant bits on disks. I have images of the actually problem that I found by taking close-in images and enlarging them and there it was! Looking like a long teardrop shaped, dark streak with a bright bit at the head end. With finer disks, only the dark streak is visible, but it allowed me to identify the zone I could not use without scratches. One of the four has so many that it is a loss.
Sorry to be so wordy, but I feel an obligation to share my story. Nothing more.

Wow, that was a response and a half. Thanks for all the time and expertise that went into it.
I’m going to have to send a little time reading it again (and maybe again) to get the full value from it. One immediate question, so no water but use WD40 instead, how often do you need to re-spray the lap during the cutting action. Is there a visual or audible clue as to when it might need another squirt?
Thanks again. I guess I’m not the only one benefitting from all the expertise that has headed my way over the course of this discussion.

New diamond laps are always going to be aggressive and it is common for them to leave scratches. They should improve over time.

However, diamond plated laps are not polishing laps and to get a great polish you need a pre-polish lap and a final polish lap. Many of the people answering above have already offered plenty of pointers on these.

You can’t get a polish just by using 1800 grit lap, that’s not even a pre-polish, I know where you are I’ve been there trying to figure all this stuff out, check out They have the BEST stuff for pre and polishing. I use the tin+ for prepolish with 8000 grit and the batt lap with 60,000 grit for polishing. Happy Cuts! And Merry Christmas!