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Strange color change garnets


#1

Hi All- I’ve recently come into a mixed parcel of what appear to be
green, champagne, and honey- colored grossular garnets from Tanzania
and Mali. There are many stones in this batch which exhibit a color
change I’ve never seen: The greenish stones change to a dark yellow
under fluorescent light, the honey and champagne stones also change
to a pale green or light amber in fluorescent. The color change runs
from approx 40% to 80% in the stones which have the property
present. I’ve never seen color change garnet of these type, just the
normal red-to-purple/red-to-amber/red-to-light green- has anyone out
there seen garnet which exhibits this different color change
scenario? They are also very clean stones, mostly alluvial and
2-10cts each.

Thanks,
Clyde Gilbert
Greenwood Studio


#2

Clyde, I purchased some rough from Tanzania about a year ago that
sounds just like the stones that you have. The main difference was
the size, all cut under 1.5 carats.

I have also seen several Mali garnets that exhibited a nice though
not dramatic color change. Many garnets do have a color change,
though it is not overly strong and I prefer to call it a color shift.

There is a lot of color change garnet out there that people just
don’t recognize. I have cut a couple of stones from Colorado that
were spessartites. They had a change from orange to gold. There are
even some coming from Tanzania now that have a true red to blue color
change.

To my knowledge all color change garnets have at least one other
significant garnet component to them, usually spessartite or
andradite. (Mali garnets are a mix of grossular and andradite).

Hope this helped.

Mark
www.upstategems.com
Custom cut/designer gemstones


#3

First check if they are natural Stones …

Ahmed Shareek