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Difficulty polishing lapis cabochons

I have difficulty polishing lapis cabochons although I have been a
lapidary for over 50 years. I recently broke down and purchased
some from Rio Grande and they have a beautiful polish ,however the
catalog states :“treatment none -polished with paraffin wax” I
presume these results in a coating which will not be permanent.I am
now concerned about selling jewelry using these cabs.

-comments anyone.


I have cut a fair amount of lapis lazuli over the years and have
found that its rare to find two stones that polish alike. I have
used leather, wood, plastic, felt, etc,. Cerium, linde A/B, Holy
Cow, etc. Fast speed, slow speed, etc. Result, I still can’t find
two stones that polish alike. For the most part, lazuli seems to
like a harder carrier and linde A. My wood laps with LA produced a
more consistant result than anyother. However, the consistancy of
the stone also had a lot to do with it. If it is a lighter blue it
is extremely difficult to polish. Likewise with the deep purple. I
believe the stones that are an even deep blue with a bit of pyrite
will polish the best.

I suggest you try either hard leather or a grooved hardwood lap with
linde A using medium speed and pressure. Just last weekend, I met
the wife of an old friend who was wearing a lazuli I had cut and set
for her nearly 30 years ago (her favorite ring) and it still looks
just great. It had been polished on wood with LA. Let me know how
it works for you.

Re the use of paraffin to polish…it does a pretty good job though
I prefer whale wax to paraffin…its harder and more consistant. As
long as you declare the polish is done with paraffin, there should
be no problem. You are correct that paraffin is not permanent
though it should last quite awhile as long as it is not subjected to
solvents or high heat. It can also be rewaxed easily enough.

Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry! @coralnut2

The only way I’ve been able to get a polish on Lapis is by using a
50,000 grit diamond belt on an expandable drum. Even at this grit
they’re fairly aggressive when new so get it broken in first. It
seems to me any stone with a waxed polish would loose that polish
with time and if subjected to steam cleaning or alcohol the loss
would be immediate.



I also do not feel comfortable selling some of the gems with
treatments that are on the market but unfortunately most gemstones
are treated in some fashion. There are a few exceptions such as
Peridot, Garnet, Iolite etc.

There is no problem selling lapis treated with Paraffin wax as long
as you disclose it to your clients. I for one do not like to sell
any gemstone treated with paraffin.

As for the difficulty of getting a good polish on Lapis, this
gemstone easily undercuts as you are polishing it. You need to take
your time and use laps that gradually get finer and finer. It is
difficult to try to jump from say a 1200 grit lap right to a final
polish. Try laps that gradually go up to a 50000 grit diamond and
see how that works.

Good Luck
Greg DeMark
Longmont, Colorado
Custom Jewelry - Handmade Jewelry - Antique Jewelry