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Working with rough garnets


#1

Hi everyone I am a newbie. At a rock swap I bought a tin of garnets
in the raw. I don’t know how to facet and don’t really want to. Can
anyone tell me how else to prepare them to use in jewelry?


#2
At a rock swap I bought a tin of garnets in the raw. I don't know
how to facet and don't really want to. Can anyone tell me how else
to prepare them to use in jewelry? 

Well, Pam, your question is about as unspecific as “I just picked up
a dog at the humane society. What grooming can I give him to have him
win the dog show?”

First of all, garnets are a whole family of crystals with about
seven basic groups and gradations inbetween. They range in color from
clear to black. I think the only color not represented is blue.

What quality are yours? How large are they? Are they crystals or
water worn pieces? Are they fairly transparent? A dense garnet will
not let enough light go through it to show off the basic color. What
kind of inclusions and cracks do they have in them? Garnets are a
metamorphic mineral and often have inclusions in them such as mica
that render them unsuitable for jewelry. They also can have wrinkles
that fold in, sort of like a raisin. Some people feel that garnets
should be tumbled first so that they will separate along those
wrinkly cracks. Others feel that the tumbling will add more cracks
because of the stresses within the stone. What size are they? Well
shaped crystals the size of a pea or smaller can sometimes be tumbled
into little stones that can be set in pre formed settings that have
little holes where you glue the rocks in. I know, you jewelry folk,
this is unacceptable to you, but we are talking to a novice that
might enjoy that.

In India they tumble polish chips of garnets and drill through each
chip to make an irregular bead that can be strung to make necklaces,
bracelets, or earrings. This is a little labor intensive for us. But
small tumbled chips might work out well in a pebble mosaic of some
kind.

On the other hand, a larger nicely colored garnet can be ground and
polished into an oval or round cabochon to be made into a ring or
other jewelry.

In our part of Idaho there exist a lot of garnets in an area north
and east of Boville, Idaho. Most of them are too dark for faceted
jewelry. The interesting feature here is that SOME of the garnets
have rutile included in the structure of the crystal. This rutile is
lined up in such a way inside the crystal that if you cut a cabochon
with the base on an outside crystal face and the apex towards the
center you can end up with a star, similar to a star sapphire. I
understand the only area with like material is underneath a reservoir
in India.

The garnet sands in this area have been used for sandpaper for many
years. Rockhounds have been collecting up there on National Forest
land for years, perhaps since the 1930s. I am sure there is a lot of
garnet from there wandering around the United States. Unfortunately
the USFS has decided to close off all access to most of the sites and
make rockhounds dig on one area which is not very encouraging.

I have seen garnets from that general area where the crystals are as
big as a softball. But most of those are “sand garnets” which are
grainy and not usable for any gem work. There are gem quality
crystals two inches or so across. Usually they have some defects that
must be worked around. The water tumbled ones from the creek deposits
don’t look like crystals any more, but may have a potential for
stars. You would have to do research online to read how to orient
them.

For the almandine garnets from around here, one of the fun ways to
look at them is to wash them and put them in a pyrex pie pan with a
little water and shine a flashlight up from under the bottom through
the garnets. Some will look like pieces of frozen grape juice. Others
will be so dark that no light can go through them. But the dark ones
have the possibility of rutile “silk” that will cut a star stone.

Have fun with your garnets, whatever you do with them. I took some
tiny crystals and glued them into a little gold pan on a tiny gold
miner figurine and gave it to my husband on our wedding anniversary.
You see, fifty three years ago he decided to court me. The very first
date he invited me on was to go garnet hunting, figuring that the way
to a rockhounds heart was through rock hunts. Well, it was a rainy
cold November day. We didn’t find any garnets worth keeping. The
water was high and cloudy. The roads were muddy. We got royally stuck
and then almost hit an aberdeen angus cow on the way home. But it was
a lot of fun, and he was a keeper.

Rose Alene, central Idaho, where the river is running full and high


#3

Hi, you can tumble polish them or if you fancy spending a bit of time
but no financial outlay you can grind flats onto them and polish
using nothing more than SiC wet and dry paper and polish on a piece
of leather using cerium or tin oxide polish. Both of these can be
had from rockshops of sometimes from companies that do glasswork.
Another polish is chome oxide and can be found in many metal
polishes (distinct green colour).

Once you have done this they can be mounted and will disperse light
quite well depending on their size and density of colour.

Nick Royall


#4

Hey, garnets can be beautiful as cabochons! Depends on color and
clarity. I found that the fastest/best polish is with tin oxide, but
other oxides or diamond may also work.

Dick D.


#5

Hi Pat. I facet It is a fairly simple process, but the
equipment is specialized, and not inexpensive. It is essentially a
process of grinding, with progressively finer grinding wheels, until
the stone is polished. But in order to make an exact shape, the
equipment needs to be accurate, and it has to be able to precisely
repeat an angle in order to polish a face that has been previously
ground.

You can make a crude faceting machine yourself for a couple hundred
dollars, but the basic setup for precision faceting costs $2000-3000
new. Used machines are available sometimes, but a misaligned machine
will double the cutting time. Most of the colored stones on the
market are cut on fairly simple machines, in low wage countries. But
most of the colored stones on the market aren’t especially well cut,
and it takes more time and expertise to produce a passable result on
a poor machine than a good one.

The first thing to look at is the garnet you have- have you tried
the “white paper test”? It is common to find garnet that looks red
when you hold it up to a light. But how does it look when it is
sitting on a piece of white paper? If it looks like a chip of red
glass, it is a good gem.

Jeff Graham passed away a few years ago, but his website is still
one of the best references in the field.


#6

If they are well formed crystals (12-sided, with defined corners) I
might wire wrap them as is. If not, I would probably tumble them to
try to get the color to show, then drill them for beads or wire wrap
them. But that is just me, and they are your garnets, after all.

Look them over and decide if you like the way they look now. If so,
use them as is, or drill them and string them. If not, do at least
some kind of polishing and decide if you like that. Rinse and repeat.
A lot of garnets are really too dark to facet, but they make great
cabochons, too!

Steve
gemsevermore.com


#7

Take them to a lapidarist! He/she will suggest the best answer
ranging from keeping them in their crystal form, to breaking them up
with a hammer and tumbling them, to the careful cutting and facteting
of extrordinary gems. Garnets can be any of these depending, and if
you bought them I hope it’s because you liked them.

Do a search on the internet and you will find garnets are cheap and
plentiful whether faceted or cabachon or tumbled, and also very rare
and expensive depending.

Alastair


#8

Pat,

If you have no cabbing or faceting skills:

  1. Use wire wrapping techniques to mount for pendant.

  2. Use miniature diamond drill, wet, through the top of the stone to
    mount as earring.

  3. Tumble with aluminum oxide grit.

Andrew Jonathan Fine