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Author Topic: "Friable" diamond  (Read 487 times)

Scratches

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"Friable" diamond
« on: September 05, 2021, 12:52:01 PM »
I'm looking for information on "Friable diamond powder" for use in polishing gemstones. Any info. on using it , success or not , availability etc.
I have a report from some years back by Jeff Graham and he gives it a positive report . Have tried "Googling" it with limited success. I have a new lap from Clarrje Trevena and would like to try using it .
John
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Scratches

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Re: "Friable" diamond
« Reply #2 on: September 05, 2021, 05:45:24 PM »
Thanks Frank ,
I already have that article by Jeff Graham . I'd like to know if any Aussie facetors have used the product, was it good or better than ,say, De beers which seems to be the most popular and is there a local supplier as I prefer to buy in Aus. rather than overseas. I have found another US article which suggests that it is only better if used with a hard lap such as a ceramic. I did see a demo of a spray form of the diamond at Tucson about 10 years ago and the demo was done with a ceramic lap . The only supplier  i know of in the US does not ship to Australia.
If I had your skill in polishing I wouldn't be chasing this product but I'm afraid I need all the help I can get.
Happy faceting
John


Faceting Frank

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Re: "Friable" diamond
« Reply #3 on: September 05, 2021, 06:11:28 PM »
I don't turn the lap on when polishing, but wipe the stone over a stationary BATT lap with 60k diamond. I rub the lap with 600 grit sand paper to roughen the surface, pre-polish is 3k on a slow BATT lap.

Bucket

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Re: "Friable" diamond
« Reply #4 on: September 07, 2021, 07:09:46 PM »
Hi Scratches, welcome to the forum. First things first, what are trying to polish? I use diamond for some, usually harder, stones like topaz and sapphire, I've also used it on garnet and zircon with good results. The diamond powder is 50,000 and to extend it I mix it with a bit of petroleum jelly and to thin it, a few drops of turpentine to a toothpaste consistency. I apply it to my polishing lap, a pewter one, with a syringe and small blobs which are worked into the lap with the stone.
For quartz and softish stones I don't use diamond, I use white cerium oxide, again on another pewter lap. I mix it so that it looks like slightly watery milk and apply it by a dropper, usually around 2-3 drops again worked in with the stone. When the lap get dry, I use water in a light spray without adding any more oxide until the lap look clean again, in other words, it's spun off the lap. The lap is only rotated at a very slow speed to avoid this happening.
The laps I use are home made and turned by a friend who is very good at getting a level surface on the lathe. They do weigh a bit as they're around 12 mm thick but work a treat. Hope this helps. You'll find another post in the forum posted fairly recently by Makkybrown regarding making pewter laps. I'm not sure if he's used them yet or not.
Common sense isn't exactly common

Scratches

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Re: "Friable" diamond
« Reply #5 on: September 07, 2021, 10:08:28 PM »
Thanks,Bucket,
I,ve been a hobby facetor for a few years. One thing I've learned is
that some facetors are great experimenters and I've read everything I can about different things that have been tried. Mostly I facet stones with lower refractive indexes -  because I haven't had access to  many sapphires and zircons. I have also cut a lot of cubic zirconia. My polishing agents are cerium , linde a and 5,000 grit diamond.
I was reading an old copy of the Facetor's Guild newsletter last week and found an article about a recipe for using  polycrystalline diamond. I have read about PCD in the past but have never found a supplier in Australia or anyone that used it .
The late Jeff Graham mentioned some years   ago about "friable" diamond and I found out that this was his name for polycrystalline diamond.
In the last year or two there have been many mentions of PCD in US faceting talk and it is available in Australia in proprietary polishing products.
Rather than buying these products which have an unknown strength of diamond in them I'm interested to get some PCD powder and try making  my own but have not been able to locate someone local who uses it and where it can be bought.
What I like about faceting is that there are always facetors who keep pushing the boundaries.
John

Faceting Frank

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Re: "Friable" diamond
« Reply #6 on: September 08, 2021, 07:54:35 AM »
I never knew anything about “friable diamond” till you mentioned it. I buy 10kt vials of 60k diamond from Aussies Sapphire for polishing everything harder than quartz. Sprinkle a little on a BATT lap with a couple of drops of baby oil and rub it in. May be possible to get a better polish than that, but I doubt if I will be able tell the difference.

Scratches

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Re: "Friable" diamond
« Reply #7 on: September 08, 2021, 11:57:07 AM »
In my previous post I should have typed 50,000 diamond , not 5,000
John

 

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