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Need Some Help Treating Zircon Today
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Author:  Greatgems [ Fri Dec 03, 2010 3:06 pm ]
Post subject:  Need Some Help Treating Zircon Today

Experiment one in progress.

1 hour at 1000c ? results pending

I need some help i have Nigerian Honey Zircon parcel anyone treat these before if so the exact process you used would be great thanks

Joshua

Author:  esjayp [ Fri Dec 03, 2010 3:22 pm ]
Post subject:  Re: Need Some Help Treating Zircon Today

I'd be interested to see your results, just a quick search around for people heat treating Zircons I came up with some tips. Take them for what you will, since you seem to be experimenting.

# Heat treatment customarily applied (usually at mine site, prior to cutting) to alter color to desirable golden yellow, blue, and colorless. Heated for a few hours in reducing environment (surrounded by charcoal) at about 1000o C. Some (about 30%?) browns turn blue or colorless, remainder develop dark patches. Repeat treatment to patchy stones at about 900oC, in oxidizing environment to get colorless, yellow, orange or red. Unaffected stones can be recycled until yielding proper color. Treatment usually yields colorfast stones, but not always. Some stones known to fade in sunlight, or change color when exposed to strong u.v. or infrared light (e.g. tanning booths!). Obtain written guarantee when purchasing.

# Sri Lankan dull green zircon is apparently heated to a dull red color for an hour which lightens the color. Reddish brown zircon treated the same way often yields colorless stones.

Heat treatments are carried out in either a oxidizing or a reducing atmosphere (or a sequential combination).

* Orangy-brown to reddish-brown zircons ("hyacinth") are heated at around 900° C in an oxidizing atmosphere which turns them yellow to red.
* Or when these brownish zircons are heated at around 1000-1400° C in a reducing environment, it turns them into colorless or blue. Some off-colors are the result of this process aswell.
* These off-colored stones, from the reducing treatment, are then reheated to around 900° C in oxidizing conditions and this results in colorless, yellow, orange or red colors.

Author:  Conny Forsberg [ Fri Dec 03, 2010 4:15 pm ]
Post subject:  Re: Need Some Help Treating Zircon Today

I put african brownish Zirkons in the kitchen oven 300 degrees Centigrade for 2 hours. Then cool until next day, 90% were colorless the rest pale brownish yellow. Sizes between 5 and 15 ct rough.

Author:  Greatgems [ Fri Dec 03, 2010 4:25 pm ]
Post subject:  Re: Need Some Help Treating Zircon Today

Kitchen oven doesnt get hot enough to treat them thats a small problem first hour with sand on top one turned red out of 6 rest are colorless blueish grey we figure it was in for to short of a time with no charcole so back in half hour to see what transpires and then results

I need exact times for process temperatures i got.

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