Would you heat a very light yellow emerald cut zircon to bring it to white?

[beaujolais]

Would you heat a very light yellow, emerald cut, zircon (not cz, zircon) to bring it to white?

I just bought one and the seller says he can heat it to get the color out. The stone is colored something like a "P" shade in diamonds. I have no real issue with warm colored stones; nor am I more prone to the whiter shade. Both are great.

Does heating damage it? Can heating go wrong?

Don't know what to do.

(Sorry, no photo or link available).

Thanks all.

 

[iLander]

No. If you like it, keep it that color.

I don''t see the point of heating (smarter PSer''s can tell you about potential damage on Zircon) it if you like it the way it is.

 

[beaujolais]

Thanks Ilander.

Well, it hasn''t arrived yet, so I''m not sure I like it yet. It should be o.k., though.

But potential damage is what I wanted to know about.

Thanks.

 

[thresh]

If the zircon is clean, 99% chance it will be completely fine upon heating. It will likely shrink imperceptibly and increase the refractive index, if the stone is at all metamict (lost it's crystal structure due to radioactivity).... although that is completely inconsequential.

Zircon is one of the few stones that you can heat at home with no experience. Some do it on the stove (right on the electric element, or on a pan if you use a gas stove), some do it in a test-tube with a lighter... I've even in a crunch for a customer heated one on the sidewalk with a torch lighter.

Essentially, heat it til it's almost the colour you want and then let it air cool. If it's not lightened as much as you want... do it more. If I buy zircon (cut or rough), I generally buy the stuff thats too dark to be ideal to save a few bucks and then heat it myself to the colour-range I like.

Again, if it's clean... the risk is essentially negligable. If it's included, leave it as is.

ps - If you're really adventurous (and you know the stone is not of Tanzanian origin), you can heat it buried in charcoal to suck up all the oxygen and often produce that gorgeous blue of zircon. If it's from near the Thai/Cambodian border, it's pretty much a guaruntee... if it's Tanzanian, it's pretty much a guarunteed flunk... and other locations are hit and miss. But, if you're going to heat it to white... you can do the charcoal thing anyways, and it will either end up blue (if your lucky) or clear (which was your original question/goal anyways).

 

[RockHugger]

How flippin cool! I may buy some zircon now just to play with them!!!

 

[Cehrabehra]

wow that is super interesting!

I don''t know what I''d do - if I wanted it the way it is or if I wanted to play around with self heating I think that would be fun lol

 

[T L]

Okay, I have a dark red zircon I want to heat now!!

 

[beaujolais]

Thanks all.

Oooo - Thresh - tell us about yourself. What do you do? Lots of great info there. Thanks. And, Welcome

- do stick around.

O.K. Ms./Mr. Thresh - I just looked up your old posts and just learned a whole lot. Um, you've got it going on for sure. Bravo.

 

[thresh]

To everyone: Hope some of you give it a try... I would definitely start with stones you''re not attached to, just to ''get the hang'' (although I bet most people could get it pretty much just right on their first stone, even if it takes a few rounds of heating). The three most important things I''ve found with this are to:

(1) keep your eye on the stone, don''t even engage in menial conversation, or you might end up lightening it more than you intended...
(2) Keep a tonal ''reference'' as close by as possible so that you know what you''re goal is like; it''s amazing how difficult it is to be sure of the absolute tone/hue of the stone when it is gradually lightening, if you don''t have a reference around.... and
(3 - which I think I said before) if you''re not reaaaally sure if you''ve lightened it satisfactorily, stop and let it air cool so you can have a good close-up look... if it''s not enough, go for round 2; I don''t know of any way to recover your colour, so undershoot 10 times rather than overshoot once!

Those warning may sound ominous, but this is a very simple/easy way to vastly improve over-dark zircon (which is a large majority of it when it''s straight outta the ground). Also be aware that the hues (''colour'') can change quite drastically. The most common shift I see is a shift of brown-ish hues to yellow-y/orange-y/peach-ish colours. Almost all my stones, cameras, etc are in storage for a move... but I will try to get you guys a ''typical'' before-vs-after shot for the reddish zircon that is so commonly follied by brown. The result I usually aim for, assuming the stone isn''t an anomoly, is a lighter reddish with peachy-flashes that I usually describe as ''dusty-rose'' coloured even though I have no idea what colour a dusty rose is, heh.

----------------------------------

Sonomacounty: Yah, I''m new around here... and it''s Mr... I guess I decided I wanted a more ''social'' and less ''science-y'' place to discuss coloured stones. Unfortunately, I think I may have just become one of the resident nerds here.

What do I do? Well in the land of coloured stones, I''m a faceter for fun''s sake (NOTE: not an ad, not a vendor), along with doing jewelry metalsmithing, which was simply because... I mean... what do you do once you have a pile of gems, and no money to pay for someone to create jewelry that you feel does them justice. I''ve made a handful of rings, and a few pendants and pins. Unfortunately, creating masculine jewelry is very difficult for me... so only one piece I''ve made do I wear (and it was my first wax carving/cast piece).

Now, what do I actually do (when not oggling coloured stones, or trying to create more oggle-worthy stuff)? I''m a 22 year old, who just completed his neuroscience undergraduate degree (well.. other than forgetting to apply for graduation, so I have to wait a semester to get my diploma). I''m aiming for a joint MD/PhD (and hoping thats not just a hockey-star dream). Biology comes naturally to me, and scientific research is one of the pillars of my world... and if I were greedy (ie - do what I want, not the monetary greed), I would become a caged-in-a-lab academic/researcher. But MDs get all the good research grants and get put in ''charge'' (even if they have no idea what they''re doing research-wise), and I want to be able to provide a life-saving service in regions where there is not access to modern medicine like most of us have (like with Medicine Sans Fronteirs). I doubt I would bother practicing medicine very much at home (Canada), unless I end up researching at a hospital...since they generally only make practicing physicians the ''principle investigator'' (ie - person in charge of a lab).

I''m working in a blow-me-away-amazing research lab at Sick Kids hospital in Toronto... where they don''t seem to follow the standard, exploitive model of ''theres always a undergrad student who''ll work for free and expect zero credit''. The first day, they said yes to me researching my own idea and having an associate professor do some of the gruntwork for me (which never happens.. generally you just do the work the higher-ups are too lazy to bother with). After 7 days, they put me as an author for an abstract submission to (one of?) the biggest neuro conference in the world. And hell, after a month they decided to send me to a conference on ''biophotonics'' (which I''m not sure is even really a word anyone uses, heh) in Quebec City, pretty much expenses covered. And thats all while both getting paid AND getting a credit (that I don''t need, but whatever) out of it... not to mention they''re doing all this for someone who doesn''t even officially have ANY degree yet. I''m pretty sure I hit the nerd jackpot, heh.

Oh and I''m a wannabe jazz pianist, vocalist, didgeridoo-ist? (australian instrument used by the indigenous people for ritual/to induce trance), dizi player (the chinese transverse flute of the commoner), djembe-er (african drum), and so on. Music is one of the other pillars of my life (the third being esoteric weird stuff )

Well now you guys know more about me than I think I know about all of you combined. I''m in a rambly mood, which is generally the only time I post... I guess the lesson here is to avoid asking anything outside of direct coloured stone questions, heh!

 

[beaujolais]

Wow, Thresh, you are pretty incredible !!

Thanks so much for your fascinating bio. Go get em!

This is just a brief reply as I''m battling a miserable allergy episode right now but I didn''t want you to think I didn''t see your post and fantastic reply.

I am in awe, Mr. Mensa.

 

[dzop]

I've played around with home and simple lab heating too. I used to be a scientist with access to furnaces. Beryl you can do in a home oven, if it gets hot enough, but the two I tried both blew up on me-- one was included, but one was clean and I was surprised the stress of a very gradual heating over 60 min and cooling over another 60 was enough to pop it. The pieces that were left had definitely lost most of their yellow, though- as promised you can turn greenish-yellow heliodore into aquamarine, without access to super-high heat or a reducing atmosphere or any of the other heating tricks.

Sapphire is harder. I have a bunch of unheated rough from Gem Mountain, MT, which was unsuitable for professional heating b/c of inclusions. Just to see if I could get color, I brought it up to ~900C in a lab furnace over several hours and cooled it gradual overnight...no luckm but that didn't surprise me b/c IIRC the melting point of rutile is up over 1000C. I then tried it in a crucible with flux at even higher T, well into the rutile melting range but at high pressure, but that just made them cloudy and recrystillized-- I think I actually melted the sapphire, or at least caused it to substantially metamorphose, even though i should've been below the melting point of Al2O3.

I also remember hearing somewhere that while the grey to blue heat treatment can be done in an ordinary oxidizing atmosphere, the fancy colors they get out of the montana material requires a reducing atmosphere. I don't know how you'd accomplish that without specialized equipment, i don't think charcoal will last too long at 1100C.

 

[PrecisionGem]

I''ve heated zircon by holding the stone over the flame of an alcohol lamp, and while this process works, it works better in an oven. The with a longer hold time is more predictable and more stable. Often the stones right after heat will look one color, but as they cool and over the period of several hours to a day or so will drift back closer to the original color.

As a point of reference, the honey brown zircon from Tanzania heats to a nice yellow around 550 to 600 degrees F. The very dark red stones need more heat. I find 840 does the trick for the stones from Tanzania. The Nigerian stones that are a honey brown color will heat to a fantastic orange, but after about an hour or so go back to the original color. You can always heat again with any of the zircons, but once you go too far there is no going back. Heat a pale yellow stone to white is no problem. The darker red ones will get patchy looking with color spots of a burnt orange and clear area''s.

With any heating, it''s best to heat the stone slowly to avoid the sudden thermal shock, and also cool slowly. Zircons are fun to play with.

 

[marcy]

I can see all of us becoming "Mad Gemologist Wannabes" and heating our zircons.

Such fun. For some reason it made me think of boiling marbles as a kid so they would crack.