How I Polish Lapis Lazuli

Now regarding the Lapis Lazuli, well the first step is the shaping on the harsher silicone carbide belts then I continue through the steps on these belts through to 600 grit.

First of all let me say that this is a stone that I have had a hard time getting a shine on. Every attempt left me with a dull finish no matter what I tried, even after using a set of diamond flat laps I still couldn’t get a result.

Then I read about resin impregnated belts for use with diamond lapping paste, these belts are knows as REZ belts and are available here in the UK from Manchester Minerals, they come in sizes to fit 6 and 8 inch expanding drums, you can also get the lapping paste from them as well.

I will provide links at the end of this post regarding sources of supply.

Now regarding the Lapis Lazuli, well the first step is the shaping on the harsher silicone carbide belts then I continue through the steps on these belts through to 600 grit. Up until recently this was as far as I could go and the results were very disappointing indeed!

But recently I bought a couple of REZ belts for my expanding wheel and two grades of lapping paste, 30 micron and 50,000 micron.

The first step with these belts is to charge them up with the diamond paste, something I have never done before but it is pretty simply. My method was to apply lines of paste to the belt at intervals then use a finger to spread it over the belt, you can use a small amount of lapping compound to dilute the paste thus making it easier to spread. This was how I charged both of my belts.

Next I fitted the 30 micron REZ belt onto the wheel and then got started, as I said it’s the first time I had used the REZ belts and had read about the dangers of heat buildup because no coolant is used. I adopted a sort of touch and remove motion with the stone, keeping it in contact with the belt for very short periods and this prevented the heat buildup.

Even though 30 micron is broadly similar to 600 grit silicon carbide in terms diamond / grit conversion tables, the diamond after a very short time started to get a shine on the Lapis Lazuli.

The next step was to change the REZ belts over and fit the 50,000 micron belt, again using the tough and remove method and very soon we started to get a reasonably deep luster on the stone.

Currently that’s where I am at however, I have ordered two more REZ belts which will be charged with 7 micron and 2.5 micron. I did this because the gap between 30 micron and 50,000 micron is huge and by adding the two extra stages a better shine should be achieved.

Once I have these other belts in the process I will write a follow up.

I am sure that what I have described is nothing new but I wanted to share this because I find it hard to find information on the internet.

I guiess my next step is to build another cabbing machine with 4 expanding wheels purely for the diamond steps mentioned above – one day maybe!

Resources:

RES Belts, Diamond paste and Lapping fluid can all be found on the following page at the Manchester Minerals web site:

http://www.manchesterminerals.co.uk/acatalog/Lapidary_accessories.html

Best regards

Dave

8 thoughts on “How I Polish Lapis Lazuli”

  1. Hi Carl,
    we don’t use anything after the final sanding to protect the stone or Lapis or any other stone except Zebra Stone because it’s so soft.

    Hope this helps

    Dave

  2. I have cut my lapis rock with a wet tile saw. Once I have a the desired shape and size I used diamond sculpting pads (8 pads) that range in grit from 70 to 3,500. This gave me a beautiful soft shine. Not like a mirror but like a medium shine on silver.
    I was wondering what kind of finish, such as a wax or other coating to use to protect the stone at this sheen?

  3. Hi Aziz,

    wow I wish I had the machinery to do this for you but sadly I don’t. However why don’t you try Howard at Manchester Minerals on 0161 477 0435 as I know they have a very well equiped Lapidary workshop, if you have no luck get back to me and I will see if I can find someone in the UK who could do it for you.

    All the best

    Dave

  4. Hi Dave
    I have a quantity of large Afghan Lapis pieces (up to 3.5 kg)which I would like someone to cut in to 4mm thick slabs and polish one side. Can you do this? If so, approximate cost? I am in U.K.
    If you can email me, i can attach photos.

  5. Hi Dave
    How are you, I hear that Shalini is in charge of the arts centre now. As you can see I have found you site. we last we spoke at Stamford we were talking about beads. The string I wan to use is 4mm or 5mm thick, preferably in Labradorite. Can you make me some and how much for 20 to get me started and by when?

    Cheers
    Graham Palk
    http://www.EnchantingArtefacts.co.uk
    07814940942

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