Gemstone treatments: discussion and questions

[gsellis]

To become radioactive, the material would have to be exposed to neutron radiation. That batch of Topaz that was radioactive was probably put inside a fission reactor chamber. The neutrons changed the atoms to unstable isotopes and they were radioactive. All the other particle radiation does not change the atoms as such. Looking up Cobalt-60, it yields beta particles (high energy electrons) and ionizes that material. Which would not be radioactive.

BTW, Cobalt-60 is synthetic. They create it be exposing Cobalt to a neutron source.

 

[iLander]

To become radioactive, the material would have to be exposed to neutron radiation. That batch of Topaz that was radioactive was probably put inside a fission reactor chamber. The neutrons changed the atoms to unstable isotopes and they were radioactive. All the other particle radiation does not change the atoms as such. Looking up Cobalt-60, it yields beta particles (high energy electrons) and ionizes that material. Which would not be radioactive.

BTW, Cobalt-60 is synthetic. They create it be exposing Cobalt to a neutron source.

Hmmmm . . . so, George, in English- keep that topaz or dump it?

 

[gsellis]

To become radioactive, the material would have to be exposed to neutron radiation. That batch of Topaz that was radioactive was probably put inside a fission reactor chamber. The neutrons changed the atoms to unstable isotopes and they were radioactive. All the other particle radiation does not change the atoms as such. Looking up Cobalt-60, it yields beta particles (high energy electrons) and ionizes that material. Which would not be radioactive.

BTW, Cobalt-60 is synthetic. They create it be exposing Cobalt to a neutron source.

Hmmmm . . . so, George, in English- keep that topaz or dump it?

Unknown. New london blue is safe. There was some that got through when it was discovered that was the hot item. Put it in a box if you are concerned and next time you do a trip to a larger area, look up HazMat in their fire department before you go. Alternatively, a college or well setup high school chemistry department should have a geiger counter too.

But remember, the drive in your car to get it checked is far more dangerous. Risks are relative and we can blow some very minor ones way out of proportion.

 

[Pandora II]

Couple of things to add here...

LD - I believe it's 200 C for the Kunzite - I'm planning on doing mine soon. I thought the chicken would be good protection for both stone and oven (in case of explosion). Must take before & after photos.

TL - checked today re nuked tourmaline - there are no lab tests available to detect this and it is fairly routine in many tourms.

Also, just thought I'd mention that the notion that tanzanite comes out of the ground brown is a long-standing fallacy. It comes out blue, but tends to have a strong yellow modifier than makes it a bit muddy and navy blue looking. The heating drives off the yellow. Also why you get different colours with a dichroscope when looking at heated and unheated material.

My own take on treatments...

Heat - fine by me
Nuking - not keen but is pretty unavoidable with some stones.
Be treatment - no thanks
Lattice diffusion - no thanks
Bleaching & dyeing pearls - no problem... find me some Akoyas that aren't bleached and I'll be amazed. They have been doing it for decades.
Oiling - fine by me
Filling - fine with Opticon in emeralds, lead-glass or other things.. no thanks
Clarity enhanced diamonds - no thanks

 

[PrecisionGem]

Pandora, actually Tanzanite does come out of the ground brown. It's kind of a root beer brown, and this color heats to a very nice blue in most cases. I have cut many of these and heated them. In the rough these stones usually show 3 different colors of brown/yellow and grey.

 

[Pandora II]

Pandora, actually Tanzanite does come out of the ground brown. It's kind of a root beer brown, and this color heats to a very nice blue in most cases. I have cut many of these and heated them. In the rough these stones usually show 3 different colors of brown/yellow and grey.

I'd always heard this, but my tutor - who has visited the mines several times - swears blind that it mainly comes out blue. I'd love to know the truth. He and I are currently having a big row about whether or not tsavorite garnet can ever contain chromium... I say that yes, some tsavorites do contain traces of chromium even if they are coloured by vanadium and he says nope, none of them contain chromium. So, I'm quite prepared to believe he is wrong on this - although he has produced a lot of photos of 'just come out of the ground' blue tanzanite to back up his claim!

 

[PrecisionGem]

Most of the rough stones I see are brown or grey. Sometimes I do see natural blues and purple. The rootbeer brown are the best, and heat to a nice blue. Grey stones don't heat well. I've been in Arusha right near the mines, and most of the rough I saw was not blue, very little was blue.

Here's a photo of the largest mining operation of Tanzanite. I took this last summer.

 

[Harriet]

P,

I can't believe you're still having that row. Ask him to look into ultramafic tsavorites.

I'm deciding whether or not I can accept heat. Uptight, I know.

 

[Imdanny]

I don't mind treatments like heat and irradiation, especially if the price is right and the treatment is stable.

I prefer untreated stones, but some stones I will accept with treatment like minor filling on emeralds, and heated cuprian tourmalines. As always, it's personal preference, and there's absolutely nothing wrong with treated gemstones, except for the prevelance of non-disclosure. I have a big problem with that, and charging untreated prices for treated gems (hello Tiffany & Co.).

Tiffany does disclose, not that their prices aren't outrageous. They seem to want to do everything up to and including covering their gems in plastic. Barf.

 

[LD]

Pandora/Gene - I believe that Tanzanite rough comes in various different colours - for example some come out of the ground pink, orange, yellow, green etc., some also come out blue and mud coloured! I've got some cut gems from unheated rough where the rough was definitely green and pink and the cut stone also (as you'd imagine)!

Here's a couple of photos I've found that I found interesting:

p.s. Pandora - 200 degrees C it is then! Thank you for that.

 

[chrono]

Pandora,
I believe that there can be some naturally blue tanzanite coming out of the ground but those are uncommon; most are brown and will heat into that beautiful blue. As far as tsavorite, I’m surprised your tutor did not consider the possibility of some tsavorite containing traces of chromium.

 

[Pandora II]

Pandora,
I believe that there can be some naturally blue tanzanite coming out of the ground but those are uncommon; most are brown and will heat into that beautiful blue. As far as tsavorite, I’m surprised your tutor did not consider the possibility of some tsavorite containing traces of chromium.

I knew that some was blue - but he maintains that 90% or so come out blue...

With the tsavorite, he agrees that the possibility is there but wants definitive lab proof and so far says there is none. We having been having a very good-natured row about it for several weeks now with me producing more and more articles and him not thinking that any of them are authorative enough. I am sorely tempted to try and buy a piece of chromium bearing tsav and give it to him just so I can be right (did I ever mention that I have a problem with 'being right' ?)

He's the kind of guy who will hold his hands up if he is wrong on something and does enjoy arguments but I sooooooooo want to win this one!

LD - nice tanzanite rough there! I love the fancy zoisites. When are you going to do Masterchef? I'm wondering whether to try cooking a few other things as well as the kunzite but need something that might react with lowish temps - nasty coloured zircons would be fun but I rather like mine as they are.

 

[LD]

Pandora,
I believe that there can be some naturally blue tanzanite coming out of the ground but those are uncommon; most are brown and will heat into that beautiful blue. As far as tsavorite, I’m surprised your tutor did not consider the possibility of some tsavorite containing traces of chromium.

I knew that some was blue - but he maintains that 90% or so come out blue...

With the tsavorite, he agrees that the possibility is there but wants definitive lab proof and so far says there is none. We having been having a very good-natured row about it for several weeks now with me producing more and more articles and him not thinking that any of them are authorative enough. I am sorely tempted to try and buy a piece of chromium bearing tsav and give it to him just so I can be right (did I ever mention that I have a problem with 'being right' ?)

He's the kind of guy who will hold his hands up if he is wrong on something and does enjoy arguments but I sooooooooo want to win this one!

LD - nice tanzanite rough there! I love the fancy zoisites. When are you going to do Masterchef? I'm wondering whether to try cooking a few other things as well as the kunzite but need something that might react with lowish temps - nasty coloured zircons would be fun but I rather like mine as they are.

Think I'll wait until after Christmas in case I blow up the whole oven! Don't want to have to take our guests to McDonalds on Christmas day! Silly question but would you wrap the stone in foil inside the chicken or just let it go in au naturale? How long do you reckon it needs to "cook" (the Kunzite not the chicken!)?

 

[Pandora II]

Pandora,
I believe that there can be some naturally blue tanzanite coming out of the ground but those are uncommon; most are brown and will heat into that beautiful blue. As far as tsavorite, I’m surprised your tutor did not consider the possibility of some tsavorite containing traces of chromium.

I knew that some was blue - but he maintains that 90% or so come out blue...

With the tsavorite, he agrees that the possibility is there but wants definitive lab proof and so far says there is none. We having been having a very good-natured row about it for several weeks now with me producing more and more articles and him not thinking that any of them are authorative enough. I am sorely tempted to try and buy a piece of chromium bearing tsav and give it to him just so I can be right (did I ever mention that I have a problem with 'being right' ?)

He's the kind of guy who will hold his hands up if he is wrong on something and does enjoy arguments but I sooooooooo want to win this one!

LD - nice tanzanite rough there! I love the fancy zoisites. When are you going to do Masterchef? I'm wondering whether to try cooking a few other things as well as the kunzite but need something that might react with lowish temps - nasty coloured zircons would be fun but I rather like mine as they are.

Think I'll wait until after Christmas in case I blow up the whole oven! Don't want to have to take our guests to McDonalds on Christmas day! Silly question but would you wrap the stone in foil inside the chicken or just let it go in au naturale? How long do you reckon it needs to "cook" (the Kunzite not the chicken!)?

I'm going to embed mine into the actual chicken - leg or breast - rather than just stick it in the cavity in the hope of getting even heating. I'm not sure how long it should be heated for so I'm going to just wait till the chuck is done. Apparently there is zero risk of it exploding - the most likely thing is to see no change at all - but I rather like my oven.

I just did a chicken on Saturday and should have done it then but forgot. DH really raved about it though - Tesco's Willow Farm free-range if you are interested which was particularly nice and much nicer than their Tesco Finest free-range ones - so I might do another one on Saturday when we are not having guests and put it to the test.

Any ideas of what to use as a scale for the before and after photos - should I get some dulux paint chart strips in pinks and purples or something?

ETA: I wouldn't use foil just in case it had some kind of effect - can't think what it would but I'm thinking chicken meat and juices are probably pretty inert. Also the foil could direct more heat to a particular point or something. Probably talking complete bollocks here...

 

[LD]

Oooo that sounds good!

Well I guess to check the before and after you'll either need a reference stone or piece of material and take photos at exactly the same time of day, same place, same settings etc! Very exciting. Like the idea of the Dulux paint charts - I know you were joking but actually that's not a bad idea! Do they have a paint called Chicken Kunzite?

Okay - here's another stupid question for you ........... I wasn't going to eat the chicken (so definitely was only going to buy a cheap scrawny one(!) because my thinking was that if the stone had been irradiated previously would that have a weird effect and would we all be walking around like reddy brek kids by Sunday?

 

[Michael_E]

I wouldn't waste your time with trying to cook gems in your oven. Even though the oven can get to 200C, anything that you're putting the gem in which has water in it can not get that hot. Well not until the water all boils off and that could take a while. If you were to wait long enough for the water to leave, you might have a very difficult time with cleaning the dried residue off of your gem, (YUCK).

If you want to mess around with heating stuff in your oven I would suggest using a heat resistant bowl and some dry sand, since it can get as hot as the oven does. It's also a LOT easier to clean off that poor gem than roast, charred bird. Does sound good though, doesn't it?

 

[ForteKitty]

That sounds like such a fun project! my oven will finally get some use since i dont bake...

What cheap stones can I buy to heat? I wont be setting any of it.. just want to see the change.

 

[Harriet]

P,
Isn't your engagement tsavorite bluish? If so, it might very well contain chromium.

 

[Richard M.]

Pandora,
Your tutor needs to spend a little time in the library. I suggest he look up a Gems & Gemology article by GIA researchers Manson and Stockton published in the Winter, 1982 edition. It's titled "Gem Quality Grossular Garnets," and is part of the most extensive gem garnet research project done anywhere in recent years.

On page 210 it states: "...there is a direct relationship between the amount of V2O3 in a stone and increasing green...Cr2O3 behaves remarkably like V2O3, although in smaller quantities (only two stones [of 105 studied] with more than 30% green contained no chromium). This suggests that generally the V2O3:Cr2O3 ratio in green grossulars is considerably greater than 1:1 but that both vanadium and chromium are usually responsible for the green in grossular garnets."

Richard M. (Rick Martin)

 

[Cabochon1]

I don't really understand why you are all fine with opticon filling for emeralds. There are still fine emeralds around that are not filled. I don't see why this treatment differs from others? Ok it will not look ugly in a few years but apart from that.....

 

[T L]

I don't really understand why you are all fine with opticon filling for emeralds. There are still fine emeralds around that are not filled. I don't see why this treatment differs from others? Ok it will not look ugly in a few years but apart from that.....

Well, like oil, opticon can be removed and reversed. It is also more permanent and stable than oil. It is very costly to buy an untreated emerald with fine saturation and no treatment. The finest emeralds are a medium dark tone and vivid, very slightly bluish green saturation, and it's very very rare to find an untreated emerald that fits that bill. Lighter toned emeralds tend not to be as included, and often need little or no treatment. Most emeralds, especially the deep dark saturated ones, suffer from too many surface fissures, so the oil, or opticon helps improve the appearance of the gem by filling these fissures. The amount of filler is so small it does not even affect the carat weight, unlike lead glass filled rubies that are more glass than ruby.

That being said, I prefer emeralds with faint to moderate treatment. Any more than that, and it's becoming a more invasive treatment.

 

[aviastar]

I feel that treated stones, especially clarity enhanced/fracture filled diamonds, provide a good cost-effective alternative for those who simply cannot afford an untreated stone. These stones are probably not for the serious collector, but I think it's great that someone just starting out can get their fiance a beautiful diamond that they will love to wear without breaking their budget.

That said, both the purchaser and the wearer should know the stone has been treated; as consumers certainly, but also so they know how to care for the stone. The polymer used in a clarity enhanced/fracture filled diamond (this is the wording that should be included with a grading report) should withstand normal wear and cleaning, but cannot withstand high heat, so things like retipping prongs can be tricky. However, if the stone were purchased through a reputable company the treatment should be replaced free of charge, no questions asked, if anything should happen to it.

So, like others have said, disclosure is key- but in general I am in favor of practices that allow people in all budget ranges to purchase, wear, and love gemstones and jewelry, as long as they know what they are buying.

 

[virgoruby]

I don't really understand why you are all fine with opticon filling for emeralds. There are still fine emeralds around that are not filled. I don't see why this treatment differs from others? Ok it will not look ugly in a few years but apart from that.....

Well, like oil, opticon can be removed and reversed. It is also more permanent and stable than oil. It is very costly to buy an untreated emerald with fine saturation and no treatment. The finest emeralds are a medium dark tone and vivid, very slightly bluish green saturation, and it's very very rare to find an untreated emerald that fits that bill. Lighter toned emeralds tend not to be as included, and often need little or no treatment. Most emeralds, especially the deep dark saturated ones, suffer from too many surface fissures, so the oil, or opticon helps improve the appearance of the gem by filling these fissures. The amount of filler is so small it does not even affect the carat weight, unlike lead glass filled rubies that are more glass than ruby.

That being said, I prefer emeralds with faint to moderate treatment. Any more than that, and it's becoming a more invasive treatment.

I've got a question...
I understand that, as far as emeralds are concerned, colourless enhancements - such as oil, resin and polymer - are generally accepted in the gem trade; however, is one treatment (e.g. oil) more accepted than others?

 

[LD]

Oiling of Emeralds goes back hundreds of years - I think, but am not sure, that it even dates back to Egyptian times. It's therefore considered "normal" for Emeralds unlike other gemstones. Opticom is a more modern version and has some advantages over oil. It is interesting because filling of other gemstones (ie. rubies for example) is generally not considered to be "normal" although this is becoming alarmingly common. So in some ways it is double standards but I guess with Emeralds you expect oiling - with other gemstones you don't buy believing anything in particular (although there's a huge range of treatments!).

 

[PinkTower]

I actually have a question about how a tourmaline "should" be heated...
Experts, please help me~thank you!

I have a unheated copper bearing tourmaline that has some grey in it, so I'd like to heat it myself at home...
Is it possible and how? And is it safe to do so?

I don't want to end up with a colorless stone or a cracked stone

I'll check my notes tonight, but I think I have heat the Mozambique material to 585 C which is 1085 F. Your normal oven can't go this high. I ramp up by changing the temperature 100 degrees per hour, hold the stone for 1 hour, then allow the oven to cool by it's self which is about 12 hours. The stone is packed in a crucible and investment powder. There is always the chance for the stone to crack. I have had some stones that were flawless crack, and I've had some with inclusions that didn't.

Gene,
There seem to be two divided camps now two major issues. Do YOU believe there is a lot of tourmaline being treated right now?

 

[virgoruby]

Oiling of Emeralds goes back hundreds of years - I think, but am not sure, that it even dates back to Egyptian times. It's therefore considered "normal" for Emeralds unlike other gemstones. Opticom is a more modern version and has some advantages over oil. It is interesting because filling of other gemstones (ie. rubies for example) is generally not considered to be "normal" although this is becoming alarmingly common. So in some ways it is double standards but I guess with Emeralds you expect oiling - with other gemstones you don't buy believing anything in particular (although there's a huge range of treatments!).

Double standards indeed... though unlike corundums, emeralds are never (?) heated to enhance the clarity (or colour)... is this correct?

 

[T L]

I wouldn't really call the flling of emeralds with opticon a "double standard" vs corundum. The problem is that corundum is heavily filled with glass and under very high heat, and most of the stone is glass at that point. The process of oiling or filling an emerald with opticon is only done under some pressure (no heat) and it is reversable, and so little of the filler is used that if removed, there would be no carat weight difference. It's really only to fill the surface fisures which are very common in emeralds. The two treatments couldn't be more different, and one is much more invasive than the other.

As far as I know emeralds are never heated, and I personally think that heating one would be detrimental to the stone. Cracks tend to grow under heat, and since emeralds have many fissues, it would be like "emerald suicide" to heat one. At least that's what logic tells me.

 

[Pandora II]

Rick you are a star - I was hoping that someone would know a good reputable source... so far he has rejected all my other attempts: Michael O'Donaghue and many others. Eugh!

LD - I fully intend to eat the chicken afterwards! Michael, you are probably right that I would be better doing a bowl of sand but for some strange reason it amuses me to use a chicken so you'll have to humour me...

Can someone correct me if I am wrong, but as far as I am aware treatments such as Opticon don't have to be disclosed as long as they are colourless and not permanent? I know oiling doesn't need to be disclosed.

Why am I okay with Opticon? Because it is reversable, improves the stone and helps durability and makes fine emeralds more accessible - I'd rather have an Opticon filled emerald that looked fabulous than an untreated stone that cost the same and looks a lot worse. Super-fine emeralds are not in my budget. I'm not really an emerald person - tsavs are my thing - but if I am buying one for someone else I do not have a problem with recommending an Opticon filled emerald whilst I would NEVER recommend a lead-glass filled ruby.

Right now I am steering clear of corundum in general unless I know and trust my source. Just too much dodgy stuff on the market.

 

[LD]

LD - I fully intend to eat the chicken afterwards! Michael, you are probably right that I would be better doing a bowl of sand but for some strange reason it amuses me to use a chicken so you'll have to humour me...

Pandora let's hope you don't have a healthy glow afterwards!!! The chicken still seems a more amusing past-time I agree! Although I'm tempted with the sand and a casserole dish! Decisions, decisions!

 

[chrono]

The level of treatment should definitely be disclosed. As for type, to me, it should be stated as well whether it is oil or resin (Opticon or Permasafe).