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[Source] Garnet rough for Anglo-Saxon inlay


#1

Hi everyone,

All the excitement around the recent discovery of the Staffordshire
Horde has motivated me to finally get going on some experiments with
the garnet inlay technique used in many of the pieces (and in many
of the pieces of the Sutton Hoo Treasure).

Does anyone have a recommendation for a source of rough garnet
appropriate for the technique?

My current thinking is that the best rough for this technique is a
bit different from the usual for faceted stones. For faceted stones,
“chunky” rough is best.

For inlay, you want relatively large, but quite thin (no more than
1-2mm when finished) “plates” of polished garnet. The individual
inlays varied quite a bit in size (l x w). The smallest shaped
pieces were only a few tenths of a mm square, but largest pieces
approached 10mm on the longest dimension! It seems more reasonable
to target working somewhere in the 5mm x 5mm range if possible, or
at least with pieces that are 5mm on the longest dimension.

From the reading I’ve done, it seems that most inlay was a true red
pyrope garnet (perhaps Bohemian Garnet?) or almandine garnet (from
Asia, pehaps Ceylon?).

I’ve surfed around on the 'net and found that most sites,
unsurprisingly, emphasize the suitability of their rough for faceted
gem cutting. If anyone knows of an appropriate rough supplier, or a
potential supplier who might be willing to talk with me about this
project generally, suggestions would be greatly appreciated.

Thanks,
Tom Colson


#2

Hi Tom,

a good source for about this is

Anglo-Saxon Studies in Archaeology and History, Vol 4.

I got a copy from Oxbow Books who I believe have an outlet in the
USA. No connection just a useful source.

I understood that when garnet was found these thin heat damaged
crystals were discarded as being no use for cutting into cabs or
faceted stones. so presumably there are piles of them in the spoil
heaps where Garnets are found! From memory they were about 1/2mm
thick.

The above book also goes into how the foil backing could have been
made, very interesting, they must have had good eyesight.

regards Tim Blades.


#3

Fortunately many kinds of garnet tend to form plates in addition to
chunks. I’ve gotten mixed rough with a good quantity of flat pieces
from India. I believe I got it from Stone Age Industries on the web.
It’s also inexpensive in cabbing qualities – less than $10 a pound.

RC


#4

Hi Tom,

I’m not familiar with garnet inlay, but it.s probably not that much
different from other inlay.

Assuming you can’t find uniformly thin pieces, a thick chunky piece
could always be cut with a diamond blade trim saw.

Starting with uniform thickness would save time when finishing the
piece.

Dave


#5

I’ve studied the Sutton Hoo collection at the British Museum on 2
separate visits. It’s clear to me that more than one type of garnet
was used. One was a red garnet, probably pyrope or a lighter
pyrope-almandine. Another is a reddish-orange garnet, maybe a
pyrope-spessartine or even hessonite. Perhaps other hues were used as
well – memory fades. Some examples are shown at Google Images.

Considering the method of construction – a thin polished garnet
slice mechanically suspended in a cloisson above a polished gold
reflector – it seems to me one would have to experiment a lot to
achieve similar colors. The gold backing would probably influence the
hue seen by the eye.

The reference below suggests that the slices were polished
mechanically since they are all the same thickness. I suspect the
artisans probably used pitch or some other adhesive to temporarily
attach thin garnet pieces to a flat board, then ground and polished
them together on a flat surface using crushed corundum or some other
hard abrasive. With care and lots of labor uniform results could be
achieved with that method and modern abrasives.

http://tinyurl.com/yjatzay

With a modern diamond trim saw it should be easy to section larger
garnets to an appropriate thickness. You might be able to use a
hand-powered grinding/polishing method as described. If I was doing
it I’d invest in a small vibrating lap which would save an enormous
amount of time and effort.

I’ve recently read a comprehensive discussion of how the work was
originally done, including probable sources for the garnet (perhaps
different than those referenced above – can’t remember). I thought I
had it bookmarked or printed an archival copy but can’t find it. I’ll
keep searching.

Maybe I can help you find the garnet rough you need when the time
comes. I have bulk sources for a number of different hues. Garnet
colors vary tremendously depending on the degree to which species are
intermixed.

It sounds like a wonderful project!

Rick Martin
www.artcutgems.com


#6

Tim,

Thanks for the pointer. I have that book as well and there are
indeed three good articles in it that bear on the subject.

My understanding of the garnet dimensions comes from the extensive
work done by Arrhenius and published in her excellent book
"Merovingian Garnet Jewelry". She measured a variety of work and
found the garnets ranged from around 0.2mm at the thinnest to around
1.8mm at the thickest.

Regards,
Tom


#7

We have several hundred grams of small Garnet rough which may be
appropriate for your project

We also have a similar quantity of small thin Montana Sapphire
rough.

Come see us at our booth # 205 in the GJX at the February 2010 Tucson
Shows and we will show you the material.

Best regards,
Robert P. Lowe Jr.