I agree with Tony. I have polished lapis(My very favorite
stone) for years first with hand or machine sanding then move to
a canvas on a very thin rubber pad backed by hard wood, it is
about six inches in diameter and I use 3000 grit diamond powder
and a spray of misted water then move to 8000 grit…then move to
a cloth(thick almost like velvetine) on the same hard wood disc
with no rubber cushioning. I can achive a glossy finish with
just a little work.
Quickly wash to clean never let sit long in cleaning solution or
the gloss will be removed. This is not as hard as it might seem
but if there is a local rock club they will be glad to give you
help I’m sure. Ron Kreml
Garnet is 7-7.5 on the mohs hardness scale…considerably
harder than Lapis (5-5.5)…and somewhat harder than agate (7).
You need pro tools…or a pro. I’ll gladly do it for you, if
you’re not in too much of a hurry (travel time
South-North-South.)
Ginny it just needs refinishing… Any lap person can do it in a
few minutes for you… If you lived down the block I would do it
for you…I used to do my pinkie ring all the time… course I’d
do it for nothing if you let me take Alan’s class.,.,.,…
calgang. Ps I’d still do it for nothing…if you lived down
the block…
John you are absolutely correct! Many porous stoned have a
tendency to absorb polishing compound and cutting oil. The
simplest way to prevent this is to soak the cabochon in distilled
water for an hour or two before you begin cutting. Diamond
compound, in combination with soaking, will eliminate the
problem completely. -Pete- Buffalo, NY
Traditional polishing methods for lapis lazuli is indeed tin
oxide on leather. Other metal oxides have been claimed superior,
chrome is the messiest, aluminium the most expensive, cerium the
cheapest. They all produce the trade mark lapis polish…orange
peel however slick.
This effect is because lapis is not a rock, it is a collection
of rocks with a great affinity for one another such as azurite,
lazulite, calcite, pyrite etc., in varying quantities all with
different hardness, toughness and polishing characteristics.
Sometimes the right combination of exposed minerals allow a metal
oxide technique to produce a high polish this is seldom a
transportable experience. Diamond on a hard surface however
will always provide a high polish as no undercutting of the
softer elements occurs. Although this is technically a ‘scratch’
polish you will see a sharp reflection in the surface.
To negate everything I have told you I should add that I have
faceted several pieces of high quality lapis with spectacular
results. Various rose cuts (crown facets only, flattened back to
girdle dimension) round and rectangular as well as pyramids.
Lapis takes an extremely high reflective glossy polish when
faceted. I use a tin lap with aluminium oxide (Linde A) to
achieve this. You also get a premium price for your unique
stones.
Amy, try polishing the BACK of your cab using your usual
compounds–this will give you an idea what they’ll do on the
stone, but should be okay. I’ve cut lapis and malachite both
using just red rouge and Zam for final polish. Do, however, wear
some type of respiratory protector–not sure about lapis, but
malachite dust can be DEADLY! Sharon Holt
Virginia; For the sake of accuracy, garnet has a hardness of 6
1/2 to 7 1/2 on the mohs scale, depending on the specific
variety. For comparison it’s more or less in the same range as
agate (calcedony). A garnet cab can be polished by hand with
nothing more than progressively finer emery cloth or paper , 320
to 600 grit, depending on how scratched the stone is, and final
polished using cerium oxide, tin oxide or aluminum oxide on a
leather buff. A strip of soft leather will serve. The only
natural stone having a hardness of 9 is corundum. Jerry in Kodiak
Peter – This is interesting – why distilled water? Why water?
Wouldn’t it just move out of the pores at the first hint of heat
from polishing??? And then what does the diamond compound do? I
know nothing about cutting, polishing, etc.
Laura, I prefer to use either distilled or filtered water because
of the level of (potentially caustic) chlorine in our area’s tap
water. Water is ideal for saturating stones before cutting
because, unlike the oil that I use as a cutting lubricant, water
will evaporate quickly after the job is done. Water fills the
pores in the stone, and prevents the absorbtion of potentially
discoloring compound and oil. When you polish with diamond you
don’t generate much (hopefully almost no) heat. That makes
diamond ideal for softer stones such as Lapis, Turquoise and
Malachite - which have an annoying tendency to crack when exposed
to high temperatures. These are, of course, my own biased,
individualistic opinions. Other folks on Orchid will undoubtedly
disagree with my thinking…but knowing the quality of the
people on this forum I suspect they will do so in a way that
stretches my understanding. That’s what I love about this place!
Best regards from the now-sweltering-hot Cradle of Winter,
Pete
Buffalo, NY
I find that stones can get quite hot using diamond, hot enough
to melt the dop wax holding the stone.In fact, I no longer use
dop wax if I will be polishing with diamond- I crazy-glue the
stone to the head of a nail and use the nail as a dop stick. I
like diamond particularly for stones which contain areas of
widely varying hardness, like chrysacolla and yowah opal. The
great advantage of diamond over tin or cerium oxide when working
these stones is that it has a much lesser tendency to undercut.
Also, the various oxide polishes may discolor a porous stone,
whereas diamond will not. IMHO.
What does one use to polish Lapis? I have fair to middling success
with Zam. But I've seen polished Lapis look much better at shows.
Since we can’t see those lapis stones you refer to having seen at
shows…
At the risk of being redundant John Sinkankas in “Gem Cutting”,lists
lapis lazuli pp. 266-267, suggests leather with Linde A or chrome
oxide. And Linde A on tin for faceted lapis. You don’t see faceted
lapis very often.
I read somewhere that waxing is a treatment for Lapis, I have never
tried it though, I use Linde A and it seems to work fairly well, know
what you mean though, I have seen some stuff at shows that looks like
it is still wet.
Lapis is most often waxed. I don’t wax. I’m a stickler for natural
just coming to grips with heat treating. And I’m sorry I can’t
recall my wheel designations. I think I just stop at 600 (well worn)
on Lapis, Sugilite and DinoBone.
If someone has a better treatment PLEASE contribute.
Interestingly, I have faceted lapis and polished it with Linde A on
wood…maple is a bit too dense…I have a custom made teak wheel
I use. Haven’t done it for a number of years though.
The Sinkankas reference simply says ‘leather’ but does not specify
what kind!! My experience says hard cow leather about 1/4" thick does
the very best job. I also have another teak wheel with grooves and
get good polish on cabs with that, though size of the stone and
groove limits its use. Make your speed about 4-600rpm if possible.
Lapis is not like jade which likes about 800rpm. Don’t use too much
pressure as lapis lazuli can fracture ( again unlike jade which loves
pressure and heat during polishing).
Cheers from Don at The Charles Belle Studio in SOFL where simple
elegance IS fine jewelry!
I am a Lapis nut. I have used Zam, Linde A, etc I also facet and
Cab. Chunky facets. Free form cabs. I use Hi-Tech Sanding and
polishing pads from 180-350-600-1200.
Then eastwind lapidary dimond pads from 3000-14,000-50,000. No more
Zam, Linde A or mess, nice and clean.
These are all flat pads cooled with water on a 8inch Hi-tech flat
lap and I finish with a buff and wax with Renaissance wax. This gets
me a water shine everytime. The wax is more for seal and finger
print protection and final bling.
One of the well known lapidary cutter on the orchid - Doug I think
suggested this rout for a ruby problem I had, which worked great, so
i used it for my other lap work and it worked great.
I would like to add my tcw to this thread. Although Sinkankas’ book
is a great resource for faceting and cabbing I have found a huge
amount of info explained just ever so slightly differently in
Christopher E Hyde and Richard A Matthews’ The Complete Book of Rock
Tumbling. This book has been invaluable to me as I have taught
myself to cut, grind, create performs for tumbled finish and hand
finishing, created pounds of hand broken tumble loads and so on. They
do a wonderful job of thoroughly explaining processes, gives all
kinds of technical and machine info, almost as good as Krey T’s
website! This book even takes you into the finish work of what kinds
of settings and uses for your finished rock and the basic steps to
creating them. For newbie’s in lapidary work or for someone just
adding that as a part of the whole jewelry making process this book
would serve you well. I found mine for cheap on eBay but even new it
would be worth the investment. Cori in Wisconsin where the rocks are
still frozen to the ground!
I go diamond all the way up to 100,000 diamond grit, and use a 3M
cerium oxide belt (white belt) or pad after the 3,000 Nova wheel.
After the cerium oxide I use 4" muslim buffs (blue, stitched) charged
with 50,000 and 100,000 grit diamond. Wash w/soapy water and rinse
between the 50,000 and 100,000 grits though. Works wonders, no wax
necessary. Does wonders for grade “B” and “Denim” Lapis too.
I cut lapis from rough cutting to pre-polish on diamond wheels. Lapis
is soft so I start on a 600 wheel and work through to a 1200 wheel. I
then do the final polish on a leather buff with tin oxide. Tin oxide
is a bit messy but seems to give a good polish.
After the cerium oxide I use 4" muslim buffs (blue, stitched)
charged with 50,000 and 100,000 grit diamond.
Diamond on stitched buffs? I don’t believe I’ve ever heard of using
diamond on something with so much surface area (between the muslin
layers)-- it always seems to be felt, wood or leather. Doesn’t this
soak up an awful lot of diamond?
