Back to Ganoksin | FAQ | Contact

Frosted black onyx


#1

I would like to make a ring and earrings with frosted Black
Onyx, approximately 10mm round, and probably three more 5 1/2 mm
round . Is it a complicated process to frost? I do no lapidary
and don’t want to go to any great expense to do this on my own.
Or is there anyone out there who does this who can suppply me?
Thanks. Cece http://www.tiac.net/users/cybgold


#2

I get frosted black onyx cabs from DIKRA in NYC - (800)
873-4572. They will ship it our from a phone call. Diane and
David are very helpful. You’ll need your tax number when you
call. Good luck, Gini


#3

I have several dyed black onyx cabs that I’d like to have a frosted
appearance, but I’m not sure of the best way to achieve this finish.
Would a glass etching cream work or is it best just to sand them by
hand? (I don’t have a sand blaster) Do I need to seal the stones
after frosting them? If so, how should this be done?

I realize onyx isn’t an expensive stone, but I’d hate to ruin
perfectly beautiful stones with trial and error. I know prehnite
becomes gelatinous when exposed to HCl, but can’t seem to find
anything about onyx precautions in a search. A few people have asked
this same question in the past (archives), but I don’t believe they
received technical assistance.

Thanks!
Pam Farren
Newburyport, MA


#4

You could try using nitric acid. Hydrofluoric acid will work for sure
but it’s really, really nasty stuff and should not be used by someone
not schooled in the proper handling of it. I personally would buy a
sandblaster. Better to go into debt a little than to risk pain,
disfigurement and death. You’ll end up using the sand blaster for
other things.


#5

How about if you put the onyx in a tumbler with some silicon carbide
for a short time. Or ifyou want to sandblast it, I live in the next
town from you.

Paula Wright


#6
I have several dyed black onyx cabs that I'd like to have a
frosted appearance, but I'm not sure of the best way to achieve
this finish. Would a glass etching cream work or is it best just to
sand them by hand? 

I assume the “onyx” is actually dyed chalcedony. I don’t think HCl
will touch it, though it might do something to the dye. Glass
etching cream is hydrofluoric (Be careful!) and might work, but what
will happen to the dye? I’d suggest tumbling with course grit,
checking often to make sure you don’t go through the dye layer.

If the dye is actually carbon (traditional sugar/sulfuric acid
method) it may stand up to chemicals pretty well.

Al Balmer
Sun City, AZ


#7
You could try using nitric acid. Hydrofluoric acid will work for
sure but it's really, really nasty stuff 

Well, not really, but sort of. Nitric won’t work, and HF will etch
it but not frost it. In order to frost it you need to use HF gas -
that’s how they make frosted lightbulbs, among other things. You’d
have to be insane to do that at home or even in a typical shop.

Sandblast with silicon carbide grit is the solution - another
solution is to just sand it down with some grit of carborundum
sandpaper. You’ll get some sort of linear pattern, but it’s cheap
and easy…


#8

Put the onyx in a screw top jar together with some clean builders
sand. Add water to the halfway mark. Take it with you when you go
jogging, tie it to the basket of your bicycle, your four year old
child, the dog…


#9

If the cabs were put back into a tumbler and run maybe 12 hours or
less in a coarse grit, the shine would be gone and the surface might
look closer to the texture of beach glass.

Larry E. Whittington
http://www.jewelrycabs.com