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 Post subject: Polishing/Faceting pearls
PostPosted: Thu Oct 26, 2017 7:09 am 
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I need to polish pearls for research purposes.
I cut the pearl in two, and then I have to polish the flat surface to see the internal structure.

What lap and oxide would you recommend using ?

Thanks,


Victoria Raynaud


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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Thu Oct 26, 2017 8:34 am 
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Victoria Raynaud wrote:
I need to polish pearls for research purposes.
I cut the pearl in two, and then I have to polish the flat surface to see the internal structure.
What lap and oxide would you recommend using ?
Thanks,
Victoria Raynaud


0-1/2 micron polycrystalline diamond on the Lightside lap will work for polishing.

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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Thu Oct 26, 2017 11:29 am 
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thomas.adamas wrote:
Victoria Raynaud wrote:
I need to polish pearls for research purposes.
I cut the pearl in two, and then I have to polish the flat surface to see the internal structure.
What lap and oxide would you recommend using ?
Thanks,
Victoria Raynaud


0-1/2 micron polycrystalline diamond on the Lightside lap will work for polishing.



I'm worried that the diamond will pollute the surface of pearl


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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Thu Oct 26, 2017 12:46 pm 
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Victoria Raynaud wrote:
thomas.adamas wrote:
Victoria Raynaud wrote:
I need to polish pearls for research purposes.
I cut the pearl in two, and then I have to polish the flat surface to see the internal structure.
What lap and oxide would you recommend using ?
Thanks,
Victoria Raynaud

0-1/2 micron polycrystalline diamond on the Lightside lap will work for polishing.

I'm worried that the diamond will pollute the surface of pearl


And you are not worried that an oxide would contaminate the surface?
Aragonite or Aragonite/Calcite cemented together with Conchiolin = Pearl
Do you think that an oxide could react or complex with a carbonate?
Does Diamond chemically react or complex with carbonates or organic compounds at room temperature?

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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Fri Oct 27, 2017 7:32 pm 
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Victoria Raynaud wrote:
I'm worried that the diamond will pollute the surface of pearl

Please define exactly what you mean by pollute, Victoria.
Thanks.


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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Fri Oct 27, 2017 8:13 pm 
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I'm not Victoria, but I'm pretty sure she means not having loose grit/polishing agent in voids in the sample. Like the SiC grit you sometimes see in poorly prepared petrographic thin sections.

It would probably more helpful to know what she is planning to do with the sample, i.e. if she needs a thin section or just a shallow cut of a pearl surface, if the use of resins would be a problem for the experimental technique(s) she wants to use, etc.

Sample prep for scientific measurements is a wide topic... ;)

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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Fri Oct 27, 2017 11:13 pm 
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Your explanation makes sense. Thanks maialetto!

I hope Victoria follows up with your question, 'What are you planning to do with the sample?"


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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Sun Oct 29, 2017 1:37 am 
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By polluted I mean visually polluted, like having black dirt stuck into small cavities.

The oxides don't get that black, and I believe, are much easy to remove compare to the oil base diamond powder.

The samples will be mainly for photos/photomicrography.


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 Post subject: Re: Polishing/Faceting pearls
PostPosted: Sun Oct 29, 2017 10:27 am 
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Victoria Raynaud wrote:
By polluted I mean visually polluted, like having black dirt stuck into small cavities.
The oxides don't get that black, and I believe, are much easy to remove compare to the oil base diamond powder.
The samples will be mainly for photos/photomicrography.

Perhaps you are thinking of traditional monocrystalline diamond pastes.
I am not aware of any oil-based polycrystalline diamond powder compounds. I employ PCD in water-based dispersions.
So, you want a specimen for photographic purposes. Any white oxide on the Lightside should polish the pearl facet.

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