http://www.goldandstone.com/garnetidentity.htm
Can anyone help me any further in a realistic identification of
these stones.
The RI is too high to measure but the original cost of the stones
prohibits a full laboratory investigation.
I someone is really interested I can send them a specimen.
These are probably a hessonite derivative garnet with zircon
inclusions!!! Where did they originate from?, and if they are
african they will have an extremely high RI just by case in point …
If you can get your hands on the Encyclopedia of Colored Gemstones
by Joel Arem it will give you some solid pictures of the coloring of
these type of garnets if I remember correctly. Hope this helps…
DM
These are probably a hessonite derivative garnet with zircon inclusions!!!! Where did they originate from?, and if they are african they will have an extremely high RI just by case in point ... If you can get your hands on the Encyclopedia of Colored Gemstones by Joel Arem it will give you some solid pictures of the coloring of these type of garnets if I remember correctly. Hope this helps...
DM, (whoever you are? 
),
I thought of the high RI garnets but the highest I can find in any
of my references is African grossular, with an RI of 1.8. Since most
refractometers I know of go to 1.81 or so, they should have been
able to determine it. Of course the reason they could not may not
have been that the RI is beyond the scale but because the bead was
still on the string. That would make RI testing kinda difficult.
Anyhow, the originator said it was also pleochroic, which should
rule out garnet since garnet is SR. I did not think the several
colors shown in the photo were pleochroism anyhow, but looked more
like the colors you see in some lead crystal beads, which could
also have high RIs. I would have bet on glass except for the
inclusions.
Jerry (still puzzled)
in Kodiak
I came across one description of these as "Vessonite (idocrase)
garnet’… so… I did a little further looking… and lo and behold…
idocrase aka vesuvianite is the exact color of the pictured bead!
Take a look here…vesuvianite is slightly pleochroic, and said to
be similar to grossular garnet … which can be a similar color and
hardness, and the two can be found in association with each
other…which could easily lead to further confusion…
http://mineral.galleries.com/minerals/silicate/vesuvian/vesuvian.htm
http://mineral.galleries.com/minerals/silicate/grossula/grossula.htm
The pic here shows deep blue anomalous interference color in
vesuvianite:
http://geolab.unc.edu/Petunia/IgMetAtlas/minerals/vesuvianite.X.html
and one more of vesuvianite with grossular garnet!
http://www.gc.maricopa.edu/earthsci/imagearchive/vesuvianite.htm
What do you think? Mystery solved? Carol
Carol J. Bova
newly relocated to Virginia
message combined
Sorry…left one additional bit out of my other post…
The RI of vesuvianite is 1.702-1.742 and 1.698-1.736 from
Carol