Dear Orchidians: I just purchased a few pieces of partially-cut and
finished ammonite and could use some advice from the lapidaries in
the group. I don’t normally buy anything like this, but got lots of
ideas the second I looked at them, and couldn’t resist. I would like
to trim off the rough edges a little, and bring them to a higher
polish. I will describe them, and perhaps you can advise me. I have 3
pieces, each with 3 trimmed, straight, and smooth sides, and one
rough, thinner, irregular edge. I would like to trim/sand this edge
and make it more bezel-“settable”. 1 piece is about 5 mm thick; 1
about 4 mm, and one 3 mm. I don’t know what the matrix is; it’s dull
grey and slaty-looking. The tops have been polished to about 600 or
800 grit, to guess by appearances. The fossilized layer appears
quite thin (no surprise). They have gorgeous blocks of bright
orange, dark red, and green colors. Given the thinness of the fossil
layer, how can I polish these? I am a non lapidary. I have the usual
metal-working tools, including flex-shaft, polishing tools and
wheels, diamond tools, sandpaper, etc. If I need to order any
special discs to do this, I will. I assume also that I will need to
protect the stone with something when I have polished it, as all the
ammonite I have seen finished were triplets with quartz caps.
Apart from quartz caps, which is beyond my capacity, what could I
use? Would a clear epoxy resin work?
Thanks very much for the advice!
Sincerely,
Lin Lahlum
ear linlah… yes ofcourse you can use clear epoxy, there’s several
out there that work vry ell one method to try is creating a cap in
plastercine and fill the form with envirotex once the form is
hardened then bake it for some time on low heat for about 4 hrs. ,
stablize the ammolite pieces w/ opticon and use envirotex as the
epoxy or use clear epoxy the type you mix together, ammolite is the
finished gem stone ammonite is the creature that it came from.
Saskatchewan has the pastel pinks ,blues etc very fine layers but
nice and you can’t and don’t work it very much,try and get a nice
finish on the ammolite the surface does not have to be lapped flat
you can grind into the colour to get at more color and to get some
depth. The cap whatever you use should not be to polished on the
underside that is glued on to the ammolite, it should be very
lightly sanded or scratched. The base stone is yes mud stone that
still has a slight trace of the petrolium product from the animal in
it so when you place the stone on a heat source to get a better
grasp of the epoxy when capping you will get small bubbles from the
gas escaping so don’t heat the stone above 200 degrees( on the
British scale)that’s it ask again if this isn’t clear. Ps no one
would help me when I first started capping etc.so I try to help
decrease thier level of frustration.
Lin, Ammolite is the fossil remains of the ammonite mollusk. Ammolite
is the trade name for cut cabochons of this material. I have bought
many top grade cabochons of this material that need refinishing.
You can see the results on my website at www.galarneausgems.com.
You can refinish your gems by using a cloth buff in your flexshaft.
I would use two buffs. One charged with 1200 diamond for smoothing
the surface and one charged with 14,000 diamond for the finish.
Ammolite does not fossilize into a super hard agate so be careful
with the pressure and heat. Do not use felt buffs as they generate
too much heat. Pressure will develop heat and chip the material.
On the edges of the material use a small rubber drum and silicon
dioxide sleeves to shape the material. I use medium grit sleeves we
used for inside sterling ring castings back in the hey day of my
casting adventures. Go slow and wear a mask because the dust is
really fine from this fossil. Using this process you should be able
to obtain a fine, brilliant finish.
hi: opticon is probably the best idea… resin will not polish well
and undercuts, superglue will work also. as far as cutting goes, use
a small diamond wheel to trim the edges, lots of speed and a light
touch will trim the edge without lubricants. small flat lap buffs
that fit in your flex shaft are readily available. get some diamond
paste,1200 micron to start, 3000, then a 50,000 will do nicely to
polish . Again, if you use a light touch you can polish without
lubricants. Use the paste sparingly. good luck Ringman
Ammolite cuts quite easily with ordinary lapidary equipment(silicon
carbide paper/grinding wheels). The matrix backing the fossilized
shell is similar to slate and cuts quickly and easily. Color layers
can sometimes be extremely thin, similar to fire agate. The shell
cuts fast, after rough grinding the stone to shape I generally start
with a quick pass with 220 grit paper, 400, 600 and then polish.
Light hand, light touch. Occasionally the shell will separate from
the backing matrix. You can embed it in metal epoxy compounds like
backing turquoise( I sometimes make my own with silver filing scrap
and dye but JB weld will work). It is possible to cut these stones by
hand (although very slowly) working on silicon carbide sandpaper.
Keep the paper wet. Working with a foredom hand piece and diamond or
silicon carbide tool bits works but do the work under a dripping
faucet to keep the stones cool. Sanding can be done with silicon
carbide sandpaper or diamond compound on foredom pads. The shell is
not as quite as heat susceptible as opal but will flake and crack
from heat buildup. Polishing can be done either with diamond
compounds or cerium oxide but the cerium may build up in any matrix
layers between the cracked shell pieces and is sometimes difficult to
remove. Better quality pieces don’t seem to have this problem as
silica penetration into the cracked shell is more complete. Most of
the ammolite on the market now is sold as doublets or triplets to
protect the delicate stone and enhance the color by concentrating
light play. Pieces can be used without the protection of quartz caps
but I would recommend informing your customers that this is
fossilized mother of pearl and must be treated gently as pearls
should always be. Lower quality pieces will show a color die off in
one direction or perhaps several. High quality pieces show color from
all angles and an absolutely smooth surface (no evidence of the
fossilized shell/matrix discontinuity). I have about ten pounds of
this material collected over the last twenty years and it is my
second favorite gemstone after fire agates. Love those color plays.
Good examples of both put most opals to shame (IMHO).