Heating tourmalines

[Barrett]

Some of you may have seen these pics on another forum but figured i would post them here for those that didn''t
me and a few others have been running some experiments with heating different colored tourmalines and even some cuprains..will have pics of those once they get back from heating but take this tourmaline crystal..deep deep green..the person that heats some of my stones bought this one from me with the intent of heating it to see the effect on the deep deep green and if he could possibly lighten it

 

[Barrett]

here is the deep green color

 

[Barrett]

Now this crystal (the green one above) was almost all gem clean..had some flaws near the top and bottom but nothing to bad..if this stone could/would have heated properly and lightened in color it would have been worth a good deal..needless to say it cracked in 4 pieces..am still waiting for pics on it
so here is a big red tourmaline 1400+cts. it's being backlit by a super high powered light..the idea was to heat and drive off the manganese to lighten the color

 

[Barrett]

needless to say once again..this huge crystal shattered into a bunch of pieces..it was even heated in investment powder...not only did we lighten the color but completely drove off the manganese

 

[Barrett]

so now it''s a sickly peridot color..no manganese left

 

[Barrett]

I am waiting for quite a few opaque paraiba tourmaline rough stones to get back..brims is heating some and my Miami guy is heating some others and a few purple crystals specs. to see what kind of change we can get..early results show that the lavender and some of the green ones turn a blue-green color but nothing bright or vivid..even opaque cuprian stones should turn similar to tanzanite opaque rough..i will post pics once they get here

 

[Barrett]

Here is a before pic of some brazilian cuprians..will be interesting to see if the blues and green/blue-greens brighten or change in color..the really interesting ones will be the pruples which are not in this photo..these are the ones that jason brims are heating

 

[RockHugger]

I was messing around and put one of my reject purple paraibas in the toaster oven (wrapped in tin foil) for about 20 min to see if it would change LOL! It didnt change...didnt blow up or crack either. *shrug*.
Was a fun experiment though!!

 

[Barrett]

LOL..heck ya..nothing wrong with trying something like that..I wish i had a kiln to heat my own..probably not a bad idea seeing as how i send all my tanzy crystals off to be heated and my tourmalines..would be much easier if i had one myself

 

[Stone Hunter]

Well it doesn''t look like heating did those stones any good if they shattered. Let us see how the other stones turn out. TFS

 

[LD]

I''m tempted to put a faded Kunzite inside a chicken and cook it to death in the oven! Don''t think it''ll work but hey, it''ll be fun trying. Not sure that the chicken will be edible afterwards though!

Amguy - even in your little parcel of Paraiba rough above there''s an interesting purple one - I know you''ve got some better ones but I''d love to see the "after" photos when you get them back. That looks a great candidate for a yummy blue!

 

[Barrett]

the thing is with those, LD..is brims is heating them..now he heats mozam. ones so he has a rough understanding of it i can do it but the other batch which i failed to get a pic of is being heated my my buddy martin over on the other forum...he is using Nassau's book to heat them properly to the exact temp. that they are supossed to be heated at..those should be interesting as they will be by the book..the problem is he is going on a skiing trip and is actually waiting for a larger crucible and more investent powder to heat those..he has one like that pinkish-brown one i posted over on the other thread he is going to heat..didn't show copper as the acting chromophore so not expecting anything fancy but you never know..without trial and error..he is also heating 2 large blue-green ones..200+ct opaque...trying to get that vivd blue or vivd blue-green color..they are all opaque but hoping for a color flip similar to tnazanite..I had 2000+cts of opaque gold and brown tanzanite heated and all turned a bright blue...i want that to happen with cuprians..it's weird with tourmalines..that top deep deep green one was trying to get a lighter color..get rid of some of the iron..but it didn't lighten at all just broke..the red one..not only lightenbed but completely changed colors..a valence switch..now with curprians it's a different story..the pruples are the ones that are fun..the oyo(oro) nigerian tourmalines ..the good cuprians were almost always a purple color then heated to get that killer blue or blue-green..now what happens if you heat an already blue or blue-green??? does it create a more vivd color? Do the greens stay green?..now bruce and i think it was brims told me that many of the mozam. purples heat to a good color but the reddish-purples or the ones with more red in them just go colorless..don't know if that is because there is a lack of CU in them or what the more red color has to do with it

 

[LD]

Now that''s really interesting about the red/purple ones going colourless. They''re irradiating Rubellites now and I wonder what the start off colour is!

Got to admit, I''ve been hankering over a Tanzanite coloured PT but have never found one! If you do happen to get a parcel that''s goes that colour - you know where to find me!!!!

 

[RockHugger]

Oh Oh, do it and let us know how it turned out! I have also tried boiling the same purple paraiba wrapped in foil (heated it up gradually). Stupid stone still didnt change.

What happens if you put them in the microwave? wasnt there some rumor where you can make perfectly cut diamonds by microwaving charcoal wrapped in peanut butter? LOL

 

[Barrett]

the cuprians have to be heated to either 450 or 500C for 1-2 hours then a 3 hour cool to change..i have it written down..actually when it comes to tanzanite there are many different temps. people use..i think lisa said she uses 550 or something..when i have my tanzy rough or crystals heated we do 350 for 4-5 hours then cool down all night..have heated tons this last year..many gem quality crystals..never had one crack or bust with the tanzy..the other thing is once the color flips with them thats it..have tried a few times to heat at a higher temp or for longer periods to try and squeeze more color but just won''t do it..once they flip at whatever temp you choose they don''t increase in color anymore..tourmalines are a whole different ball game..they are so packed with many different elements that each one is different..that deep red busted one above cost $200..after that happened and i had that deep green one i wasn''t going to try heating that one but sold it to the guy who heats my stones so he could try and that one busted also..$200 that one cost..so 2 $200 stones now just chips..well the deep green stayed into 4 pieces

 

[chrono]

Yes, I’ve followed Brim’s heating trials with interest as well. Do keep us abreast of how things turn out. This is very much like my chemistry labs in trying to determine why each one behaves different during/after the heating process except the end product might not survive or end up worse than before.

 

[RockHugger]

I would have cried if that beautiful green tourmaline busted for me. It was so pretty how it was!

 

[T L]

Date: 2/19/2010 12:50:31 PM
Author: amethystguy
LOL..heck ya..nothing wrong with trying something like that..I wish i had a kiln to heat my own..probably not a bad idea seeing as how i send all my tanzy crystals off to be heated and my tourmalines..would be much easier if i had one myself

A kiln is typically used to do this (like a potteryn kiln) and the temperatures are very high. You must also let it slowly cool. Gene knows all about heating tourmalines.

 

[lelser]

Yea, I use a programmable kiln, and start my tanz heating at 425C and then work my way up to 1000C. Only had to do that once but I basically keep heating it until either I have a color I like, or all the brown/yellow is gone.

Tourmalines are a COMPLETELY different game. Because I buy most of my tourmaline in lots, I can use one or two smaller pieces to test heat until I find the right recipe for that set of stones. Usually that works but tourmaline is so variable in it''s composition that sometimes you get something just weird.

Cheers,

Lisa

 

[Barrett]

wow..1000C? Dang thats hot..yea Lisa you are pretty knowledgeable when it comes to heating stones especially tanzanite..I have taken notes when you have posted on it before..you usually heat already cut stones, correct? i never have..only pieces of facet rough and crystals(i never have meaning I haven''t had one of my buddies heat one for me)...the thing with the big red one is the guy who heated it and busted it has heated numerous reds and greens before without busting onbe..of course this was his largest but you live and learn..here is another one almost identical to that first big green one..this one is about 200cts larger..548.5cts ..

 

[Barrett]

sorry about the pic quality..i took this one real fast

 

[Barrett]

as you can see this one is almost identical to the one above..it''s that deep deep green..or yellowish green..this one won''t get heated though..since that last one broke...this one should be left as is...although..sure would be nice to get it to lighten up..save for a few flaws it''s extremely clean..just to dark..if you could lighten the color it would be worth thousands

 

[chrono]

Actually, the cooling part is quite critical as well or so I’ve been informed and is a controlled cooling method.

 

[lelser]

Date: 2/19/2010 3:06:01 PM
Author: amethystguy
wow..1000C? Dang thats hot..yea Lisa you are pretty knowledgeable when it comes to heating stones especially tanzanite..I have taken notes when you have posted on it before..you usually heat already cut stones, correct? i never have..only pieces of facet rough and crystals(i never have meaning I haven''t had one of my buddies heat one for me)...the thing with the big red one is the guy who heated it and busted it has heated numerous reds and greens before without busting onbe..of course this was his largest but you live and learn..here is another one almost identical to that first big green one..this one is about 200cts larger..548.5cts ..

I only heat cut stones, but will sometimes saw off a small corner to see if something is heatable before I invest the time to cut it. I discovered that Chorme tourm is unheatable, so that influences what I''m willing to buy, and how I''m going to cut it, where with a regular tourmline I can usually tweak colour on a dark stone.

We run the kiln overnight, since it uses the same outlet as my faceting machine and has a pretty serious draw as it heats. Tom jokes that I run downstairs in my PJs to see what the stone fairies have left me

 

[Barrett]

I think it was you, Lisa, that mentioned i should have sawed off part of that big one to heat first..stupid me didn''t even think of that...duh...won''t make that istake again..granted it wasn''t a super fine piece of facet rough but a 1400ct Maine tourmaline still can toss some weight around..next time i will do just that and saw a piece off to try heating first...yea chrono..the guy who heated that big red doesn''t have a programmable oven..which is why next time something like that will go to brims or Martin so they can step by step heat and cool in increments

 

[RockHugger]

I just wanna touch it!

 

[T L]

Everyone tells me to heat my six carat purple cuprian cushion, but I just cannot bring myself to do it. I am not only worried about fractures, but it''s rare color, and there''s something to be said for an unheated, untreated cuprian.

Cool pics amguy. Thanks for sharing them. Nice to see you back on PS.

 

[Barrett]

a rare purple color..may not be that blue or blue-green that the masses want but it''s a more unique and, like you said, rare color...i would keep it as is..plus you can always heat it in the future in need be but you can never ..umm..unheat it