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Stone polishing question


#1

Hi, I have just set a Lapis stone into a silver ring, and I was
wondering if there is any way I can increase the shine on the stone.
Can I use ZAM, with a felt buff, if not what would be the best way of
increasing the shiny finish on the stone (I am new to this stone
polishing stuff so any help would be great ).

Many Thanks for all your help in advance

Paul Townsend
www.beau-jangles.com


#2
Can I use ZAM, with a felt buff 

Hi Paul, For lapis and other soft stones, ZAM does a great job,
though I wouldn’t use a felt buff; I would think it might actually
scratch a soft stone the way it will scratch metal. Personally, I
use the same kind of soft buff I use with rouge.

Beth


#3
  I have just set a Lapis stone into a silver ring, and I was
wondering if there is any way I can increase the shine on the
stone. 

Hi Paul, For future reference, it is usually best to address this
question before the stone is set in the ring. You have better access
to all the surfaces of the stone, and don’t risk altering the bezel.

Lapis can be tricky, because there are different grades and
treatments out there. If it is solid blue, natural untreated and
undyed lapis, ZAM is probably a good choice in a pinch. Ideally,
Linde A (high grade aluminum oxide?) or chrome oxide on leather are
better choices, if available.

If the material is of lesser quality and mass produced commercially
cut material, it may be filled (stabilized) with a material that will
undercut, resulting in more of an “orange peel” effect than you have
now. It may have also been “polished” with paraffin, which might be
the reason you have a less-than-desirable polish now. If your lapis
has pyrite inclusions, you also have to be careful not to undercut
the lapis away from the pyrite, leaving the inclusions as raised
bumps.

If you are going to try this, I would recommend a hard felt buff, as
opposed to a muslin buff you might use on metal. The harder the buff,
the less likely it will contribute to undercutting.

Also, be aware that the original process of “cutting” the stone
should involve sanding steps that take the surface of the stone to a
very fine finish before the polishing step. If a commercial cutter
only takes it to a 600 grit sanding then “polishes” with paraffin as
a shortcut, you will never get a fine polish on the stone without
having it recut properly.

You should also be aware that, in a ring, lapis will probably lose
whatever polish it has over time. Rings take a lot of abuse,
abrasion, etc., and lapis is a relatively soft material. The more
often the ring is worn, the more quickly this will become evident.
Lapis isn’t really a great choice for rings… but that doesn’t ever
seem to have stopped people from putting tanzanites and opals in
rings! :slight_smile:

Good luck,
Dave
Dave Sebaste
Sebaste Studio and
Carolina Artisans’ Gallery
Charlotte, NC (USA)
dave@sebaste.com


#4

Paul, I usually use diamond paste on a felt lap or even a hard wood
lap to polish lapis, which never takes a high polish. To increase
the sheen, heat the stone slightly and rub in some carnauba or
hardwood wax. Pate wax, not liquid, let it dry and buff it.

Wayne Emery


#5

For polishing lapis, I have not tried Zam. I have, however,
polished lots of lapis and always use 14,000 grit diamond paste on a
felt buff. This can be either on your flexshaft or polishing
machine. Keep a dish of water nearby to dip the stone in - often - as
it gets hot. I like to use a slow speed and just keep going until
the stone looks the same wet or dry.

Bill


#6

Hi, all, To Paul, on the topic of Lapis: you can restore the finish
that (I’m assuming) may have been either “pickled” or tripoli’d off
or your ring’s stone by using a thin slurry of Linde A in either
white vinegar or Windex – the goal being to affect the pH at the
same time as delicately rubbing down the surface – on almost any
type of buff you’d prefer. My personal choice is split leather,
using the coarsely “sueded” side to carry the polishing compound,
but it’s more the compound than the carrier that counts. Be sure to
keep the lap/buff surface damp, to reduce the chance of stone
breakage from overheating, and wear a dual-canister respirator to
protect yourself from both the copper and alumina dusts/mists, which
can be lethal. Hope I’ve helped demystify things a bit.

All the best,
Doug


#7

Another method I’ve found useful for repolishing already set soft
stones is to use the polishing compound, Chrome oxide. Linde A
whatever on a strip of buckskin. Moisten the leather and apply the
compound as a slurry. You can fix one end of the leather strip in a
vise, hold the other end in your hand, draw taut and rub the stone on
it. Either that or fix the piece firmly in a ring clamp or on a
mandrel and use the leather like a shoeshine rag.

Jerry in Kodiak


#8

Hello Paul, Just a comment - Dave Sebaste is right on. You should
also be aware that, in a ring, lapis will probably lose whatever
polish it has over time. Rings take a lot of abuse, abrasion, etc.,
and lapis is a relatively soft material. The more often the ring is
worn, the more quickly this will become evident.

I love the look of lapis and set some (with diamonds) in a ring
about 20 years ago. The lapis is still a lovely blue, but the
polish is long gone. I’ve worn the ring for weeks at a time, but
not all that often over the 20 years. I considered trying to polish
the stones in the mounting, but have decided it’s not worth the
trouble. I wish I’d had Dave’s input before I used lapis. Judy in
Kansas

Judy M. Willingham, R.S.
Biological and Agricultural Engineering
237 Seaton Hall
Kansas State University
Manhattan KS 66506
(785) 532-2936


#9

Hi Paul, You’ll find it difficult to polish Lapis once it has been
set. Any abrasive which is hard enough to polish the stone will also
cut into the surrounding metal. Can you remove the stone without
damaging the setting?

Lapis can be a tricky stone to polish. Unlike most Lapis
is a rock…a conglomerate of several different minerals in varying
proportion. Those minerals range a good deal in both hardness and
toughness; so it is easy to abrade one part of the stone more
quickly than another. I avoid this problem by using a graduated
series of diamond abrasives on a Graves spool polisher. (Diamond is
so much harder than any of the minerals in Lapis that the variations
within the stone don’t matter.)

Polishing a stone which is already set is usually an exercise in
frustration… :-/ Remove it first, if you possibly can.

-Pete-


#10

There has been a lot of good posted in this thread. As
a lapidary as well as a goldsmith, I would like to add that it is
impossible to polish out a stone, any stone, while it is set. When
you attempt to do this, assuming that you use the correct polish
techniques, you can get a great polish on most of the stone, but
there is an area next to the metal where is impossible to polish the
stone unless you cut away the metal. On a bezel set, this leaves an
unpolished halo around the stone at the bezel line. For a prong set
stone, you will have an unpolished area surrounding the prongs. I
have tried using knife edge tools to eliminate this but in all
cases, the difference between the re-polished area and the area
near the metal was quite obvious. The best solution is to remove
the stone and then remove the wear from it by basically re cutting
the stone. I start with a light brush on the 280 grit wheel to
remove any deep scratches, then on to the 600 to get it back to a
pre polish point. A “QUICK” trip to the polish wheel will finish
the job. I emphasize the quick because the more time spent on the
polish step, the more undercutting and orange peel effect you will
get.

Don


#11

All,

Been watching the thread on lazuli over the past week and find
everyone’s input interesting and mostly right on the mark. Re Judy’s
comment however, about 'having Dave’s input before using lapis", I
only wish to say that the beauty in this stone is not in the
polish…rather its in the color. In fact, I like to finish it on
1200 diamond and then NOT POLISH IT! The result is a very smooth
surface but not a shiny one. This tends to show the very best of
color and lessens the problem of having a stone partly shiny as the
polish begins to wear off. Just another view.

Cheers from Don at The Charles Belle Studio in SOFL where simple elegance IS
fine jewelry!
@coralnut1


#12

Hi all,

If the lapis has gone into the pickle it’ll likely be etched enough
to require a re-sanding before polishing. It’s soft enough that you
can do this by hand. I use 2000 grit wet-or-dry silicon carbide paper
which you can get at most hardware stores and at autobody supply
shops.

If you can take the stone out, glue it up onto a dop stick in the
usual way, hold the paper in the palm of you hand, and gently re-sand
the stone all around while applying lots of water. If you can’t take
it out of its setting you can glue the sanding paper onto a popsicle
stick and then cut the stick to shape with a knife to get into
corners and the “shadow” areas beside the prongs. Use a light touch &
be careful not to sand grooves. Then polish.

Cheers, Hans Durstling Moncton, Canada


#13

Jerry, This is an excellent idea! Have you every tried polishing a
set stone in that manner with Diamond paste? If so, what mesh number
would you suggest?

I’ve always preferred to remove stones (of any type) from their
settings before repolishing. Your suggestion has me rethinking that
assumption. Thanks! :slight_smile:

(This is why I love Orchid. Jewelers and Lapidaries frequently have
different solutions for the same problem. Sometimes one solution is
much more efficient than the other. We all benefit from the
cross-crafting on this forum. Once again, hats’ off to Hanuman for
providing the opportunity!)

-Peter-
Buffalo, NY, USA


#14

Peter, No, I’ve never tried polishing the set stone with diamond
polishin past but I read another message in this thread a couple of
days ago which recommended using 14,000 diamond on lapis. Sounds good
to me. I’ll try it. Jerry in Kodiak