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.
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
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
It sounds like a wonderful project!