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Demantoid Garnets

Many thanks to the person who provided the link to the article about
demantoid garnet. It answered many questions I’ve had about Namibian
demantoid (a small trickle of rough material from Namibia has been
finding its way to the American market, but I think most I’ve seen
should be described as andradite, not demantoid, because it is
brownish-green; perhaps it’s from another source in Namibia).

There are three “green garnets,” all different species. Demantoid
comprises the green to yellow-green colors of the andradite garnet
species and is uniquely brilliant and fiery. Tsavorite, the other
green gem garnet, is a member of the grossular garnet species, as are
the lovely Merelani Mint stones. Both are brilliant but don’t
compare with demantoid. There’s another green garnet species,
uvarovite, but the crystals are small and occur only (to date) as
druses. Demantoid is the most valuable of all the garnets, with
1-carat Russian stones retailing up to $2,500 a carat and fine
3-carat stones up to $15,000 a carat when available.

The article raises an interesting point. The new material lacks the
byssolite asbestos “horsetail” inclusions that are characteristic of
(and add value to) the Russian stones from the Urals. This is
something jewelers should consider when purchasing stones. There are
customers (and gemologist/appraisers) who will never accept a gem as
true demantoid without the byssolite inclusions. This is one of
those strange situations that arise now and then in the gem market
and is settled, ultimately, by consumers. I suspect that the genuine
Russian stones will continue to enjoy a price advantage, at least for
a time. New Russian material is entering the world market, and from
my own observations I’d guess there’s more of it than this article

Jewelers should also be aware that despite its great beauty,
demantoid is the softest of the garnets. It ranks around 6.5 on Mohs
scale and should be treated like tanzanite and other “tender” stones.
Pins, earrings (yes, there are demantoid pairs – I have several)
and pendants might be better choices than rings to showcase fine
demantoids. There’s also a trade-off between the deep, rich chrome
green stones and the lighter green to yellow-greens. While brilliant
and beautiful, the deeper greens display less “fire” than
lighter-toned stones: darker body color masks the dispersion colors.
You have an esthetic choice; either way, the stones are stunning.

Rick Martin