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Small scratch on cabochon


#1

How do you polish a small scratch. The cabochon is 8mm . What products work best ? Mark


#2

what is the cabochon material?


#3

Depending on the material and depth of the scratch, you might be able to polish it out with Zam . You can buy small wheels for your flexshaft that will allow you to work through progressively finer grits of diamond paste in syringes. Go to Kingsley North and look at Crystalite products. 8mm is small. I have been able to work a stone, even that small, while still in the setting on my resin diamond wheels, but you will also have to re-polish the setting. A picture and something about the material would help others reply. Good luck…Rob


#4

Hi Don
I think the stone is jade .I got it ten years ago . By the way your web site is great. Mark


#5

I am Rob. Don and I are brothers. Jade is hard o polish. I am not sure how I would do it in a setting…Rob


#6

Just two words can describe setting of a Jade ornament…"Be careful"
Jade don’t like files, burs or any other pumice wheels!

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#7

When I am polishing Jade and it gives me trouble, especially orange peel, I try polishing it on a dry very worn 600 grit expansion belt. For reasons that others will have to explain, the polish pops up with no orange peel. Depending on how deep the damaged area is and where ti is, you might try this by hand or on a flex shaft wheel with a small piece of worn 600 grit…Rob


#8

Hi Rob
I used diamond polishing compounds in the syringes . Started with 800 1200 1800 and up . It went from a small scratch to bad to ruined .I used felt bobs . The surface Got bumpy . I do not know why i was unable to smooth the stone or get the polish back .I tried different rpm but it made know difference . Thank you for your input.
Mark


#9

I think the felt bobs are your problem. They will tend to pull out particles from the jade. You will need a harder surface for the diamond polishes. You could use wooden dowels in a flexshaft chuck or perhaps cratex (rubber grinding) wheels or a small drum sander for your flexshaft with silicon carbide cylinders. Perhaps even silicon carbide or emery sandpaper with a split arbor. A little water or oil for lube would probably be good if your surface is really rough, but from a frosted surface, as was noted, a dry 600 silicon carbide grit would work. A lapidary would typically work this on a resin wheel or a firm rubber backed piece of sandpaper or a canvas belt on an expanding drum impregnated with diamond grit and worked wet. Polishing would be on leather with an oxide polish or diamond grit at 14K and maybe then 50K, but a wood surface would probably also work, although since it is hard you have to move the jade continually to avoid flats and hit all of the surface. Felt wheels are not going to work for any lapidary material with the potential to orange peel, pull out or pit. A hard felt buff or felt pad on rubber may work better for some things. But for jade, leather is preferred, generally with a hard backing. Hope this helps. It isn’t hard once the right approach is used.


#10

I should have also added that if pull out or orange peel become a problem with the methods I specified (using a hard rubber backing or something with some “give” then one would use a sharp sanding paper or a diamond grit on a hard surface. In the OP’s case he could try diamond impregnated in wood dowels, since it is only one piece and (I’m guessing) a fairly small stone. There are phenolic or wood (usually rock maple) “spools” which have concave grooves in them which can be used to work problem stones like this. You just have to keep the stone moving so that all parts of it are polished and all about equally (no flat spots). Since the OP’s stone is mounted, a dowel would probably work better than a concave spool, since a jewelry piece might make twirling the stone all around so that all parts reach the concave surface impossible. And the dowel would be easy to find, a concave spool, not so much.


#11

Hi Roy
I removed the stone from the setting . Thank you for the many different tips . I will try a wood dowel and take it from there and try your other methods if needed . The felt bob was extra hard . I also applied a extender solution as recommended by Rio Grande to the bob . Thank you again Mark