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[Gem Treatment] Zoisite to Tanzanite


Does anyone around here know how hot and how long to cook zoisite
into tanzanite?

Does anyone around here know how hot and how long to cook zoisite
into tanzanite?

Try 600deg. Celsius. or 1112 deg. fehrenheit. for about 10 min. Just
make sure there are no cracks, needles or inclusions in the stones to
be cooked. If there are any then either remove them or at least make
sure they are open to the surface for the gases to escape when the
stones are heated or you will have a badly shattered stone. Personally
I prefer to preshape the stone then heat it embedded in a pot of dry
pop powder. Leave it to cool slowly in the oven (switched off) and
almost always I get a beautiful color. Good luck, Mohamed


Manmountain, According to New Era Gems- Tanzanite Heating
Instructions: “Most Tanzanite should be heat treated after being
cut.After you have cut your gem and after you have removed all
inclusions,heat the gem in a Burn Out, Casting Oven. First, place your
finished gem in DRY casting investment, leaving about one inch of
investment as insulation on all sides of the gem.(More than an inch
is fine). We use an old coffee can, fill it with investment, and then
just place the stone in the middle. Then slowly, over a 6 to 8 hour
time period, raise the temperture to about 1000 degrees fahrenheit.
Hold this temperature for about an hour, then let the stone cool down
slowly in the oven. We recommend you start the process in the
morning, then about 5:00 - 6:00 p.m. turn off the oven. By the next
morning the oven should have cooled down, and you can remove your
finished Tanzanite.” Ive got sme but haven’t faceted it yet.By the way
the folks over there might heat it for you (esp. if you purchace the
rough from them).Keep me posted on how it turns out. Their e-mail if
you have any more questions is or
fax:1-916-272-2985, or they are listed at 1-800-752-2057. I’ve
purchased some rough from them in the past in a gem show in Chicago
and been satisfied, funny now that I’ve moved close to rattlesnake
road, I’ve yet to visit them.Good luck and hope this helps. Don