why is nuking unsafe?

[Arkteia]

If it is not detectable by modern methods, it just means that there is no serious trace radioactivity.

From what I understand, nuking by radioactive isotopes merely alters chrystal lattice of the substance (stone) and it is permanent because initially the stone was stable and not radioactive. So there is no danger in changing tourmaline into, say, radioactive polonium just by nuking it. I mean, it implies treatment which is not totally natural but still...

As long as Geyger count does not show scary numbers it should be fine.

 

[chrono]

An irradiated stone can be safe if it has been put away for a long enough period; I believe that all nuked blue topaz in the US are safe for wear due to regulations. Correct; the irradiation treatment is permanent and will not change the stone into something else completely different.

 

[T L]

There are two types if irradiation performed on gems. One type has to do with electron bombardment of the crystal, and the other has to do with neutron bombardment. Stripping electrons from an atom does not cause radioactivity and hence there is little to worry about. Most light colored blue topaz is irradiated that way. However, if you isolate neutrons from the nucleus of an atom, you are exposing radioactivity. Your husband the physicist, can probably speak to this better than I can. I just provided a very simple explanation. Darker blue topaz is typically bombarded with neutrons, and it has to go through the nuclear regulatory commission to be sold in the United States. Many dealers just stopped selling it.

 

[Arkteia]

But this type of irradiation should be detectable. Trace radioactivity, it is measurable. People seem to be concerned with irradiation of stones that is "not detectable". With modern sensitivity of radioactivity-measurine devices (honestly, I do not know what they use nowadays, it is not Geyger counter) any minimally significant radioactivity would be detectable.

What I want to say is that it is probably OK to buy red tourmalines. Or any other stones that have been subjected to low-level irradiation. My preference would be unheated stones, but this, luckily, is detectable.

 

[stone-cold11]

Ya, if the Geiger counter for the stone is not higher than the background radiation, it is just as safe as anything in the background.

 

[minousbijoux]

Wow, TL, you amaze me how much you know! Now you all have me wondering about some very high quality london blue topaz briolettes I bought at a gem show about 5 years ago. The vendor is totally upstanding and specializes in Indian jewelry and gems. Would it have been regulated in India at that time, or would it have been regulated upon entry into this country? In other words, should I be looking for a geiger counter?

 

[chrono]

Crasru,
From a health and safety standpoint, it is safe to purchase a red tourmaline. However, from a treatment disclosure standpoint, more often than not, there is no disclosure that a particular red tourmaline has or has not been heated, then nuked to achieve that super red colour. And that, unfortunately, is not detectable at the moment. Well, actually, it might be but it is not cost effective, IIRC.

 

[Lee Little]

Though there is little possibility of residual radiation in Blue Topaz do not think that the law or the government is protecting you from it. There is no such inspection on small packages coming in from foreign countries where there are no such regulations. Best regards, Lee

 

[minousbijoux]

Lee:

Thanks for that clarification - so gem shows could be really setting off geiger counters and no one would notice...

-Minou

 

[Arkteia]

Do they sell Geiger counters for gemology labs? I never thought of buying one, but it may be not a bad idea.

 

[iLander]

I have a small staff badge from the Manhattan Project and I wanted to check the radiation level. I took it to a fire station, many of them have geiger counters. When the guy turned it on, the needle jumped and went nuts. I freaked out! But he smiled at me, and said "I have to adjust it to screen out the background radiation level". Once that was done, the badge tested clean.

My point is, there is a LOT of radiation in our world!

Many objects give off some low levels of radiation; antique dishes (antique red Fiestaware had radioactive glaze), some granite countertops (search nytimes.com for story) and apparently, the "background" (the entire world around us). Even much of our food has been treated with gamma radiation. It's everywhere.

If you have something in particular you want to test, call your town's non-emergency fire department number and ask which station has the gieger counter. I'm sure they'll be happy to help.

 

[morecarats]

Your biggest danger with an irradiated gemstone is not the radiation, but color fading.

Some irradiated gems lose color when exposed to strong light or to heat. Blue topaz seems to be fairly stable, but irradiated spodumene (especially hiddenite and kunzite) is known to sometimes lose color. There has also been a lot of irradiated orange/brown topaz in the market, often sold as "imperial topaz," that is famous for color fading, often achieving a completely colorless state after some months. Perhaps they should market is it as "color change topaz" instead.

Since irradiation is so hard to detect, the home brew method among some Thai gem dealers is to put suspect specimens in the strong Thai sun for a couple of days to see if they fade.

 

[minousbijoux]

Thank you Morecarats. This kind of thread is exactly why I love this place!

-Minou

 

[T L]

Ilander,
Very interesting, but you're right. Most of the radiation we get is from the sun. Althought our magnetosphere shields us, some still gets in, and there's actually quite a bit of radiation coming from the big bang itself, and far away supernova explosions. Radiation from atomic blasts can stick around a long time too. The Bikini islands, where many nuclear tests were done, still is not safe for islanders to live in, even some 60 years after the last tests.

Don't forget to wear your SPF!! LOL!

 

[LD]

But this type of irradiation should be detectable. Trace radioactivity, it is measurable. People seem to be concerned with irradiation of stones that is "not detectable". With modern sensitivity of radioactivity-measurine devices (honestly, I do not know what they use nowadays, it is not Geyger counter) any minimally significant radioactivity would be detectable.

What I want to say is that it is probably OK to buy red tourmalines. Or any other stones that have been subjected to low-level irradiation. My preference would be unheated stones, but this, luckily, is detectable.

About 8 years ago, in the US, a huge batch of London Blue Topaz was found to have high levels of radiation. It was quarantined and couldn't be sold until it had "cooled" off. I believe there are incredibly stringent rules now about this.

I can't find the articles about it now but here's an extract from GemSelect's website on the subject:-

"London Blue Topaz is typically produced by exposure to radiation in a nuclear reactor. When topaz is exposed to fast neutrons, the radiation changes the color centers, producing the deep blue color. Subsequent heat treatment is often used to lighten the inky color. Material treated this way is likely to be radioactive and may require several months of storage before the radioactivity decays to safe levels. There are very strict rules in place to protect not only consumers but also the cutters and gem dealers who handle these gems on a daily basis."

 

[Arkteia]

Your biggest danger with an irradiated gemstone is not the radiation, but color fading.

Some irradiated gems lose color when exposed to strong light or to heat.
Since irradiation is so hard to detect, the home brew method among some Thai gem dealers is to put suspect specimens in the strong Thai sun for a couple of days to see if they fade.

You know, MoreCarats, I think I have such stones and I think I have once posted the story about them as a question. They were bought by my father in 1977 I think in Laos. Three huge beautiful stones changing colors from amazing grape-purple to blue in daylight. Sold, of course, as alexandrites. None of us, of course, had seen a live alexandrite so everyone was happy. So they were made into earrings and a ring, my mom wore them, as later did I. Then I moved here and it took me a while to get them. To make a long story short, the color change almost disappeared with time. Now they look as not too saturated, lavender-violet amethysts. I am not wearing them any longer.

I thought it was a certain synthetic that faded with time but now I think they have been irradiated. I do not know about the techniques used in 1977 but I bet irradiation was one of the simplest ways to achieve desired effect.

 

[digitaldevo]

As stated, it depends on type of irradiation used. FOr example, Cobalt-60 irradiation is being commonly used by Embarad in Brazil to nuke everything from kunzite to tourmalines to beryls to quartz to who knows what else, lol. Same method is being used in Pakistan/Afghanistan to treat "imperial" topaz, "hiddenite", darken lt. p;ink tourmalines into nice dark saturated ones, etc. Cobalt-60 leaves behind nothing. They even use this same irradiation on some of our foods here in the USA. It is supposedly totally safe due to supposedly leaving nothing behind. I know it does not register on a Geiger.

The biggest problem with irradiated gemstones is many tend to fade back to their original or other nasty combination of colors over time. They tend to do so very quickly when exposed to direct sunlight. Some stones like Kunzite irradiated to "hiddenite" do not last long at all in sunlight, where as red and rubelite tourmaline can take the treatment, be annealed with heat(as they call it) and the color is permanent.

 

[LD]

DigitalDevo - why was there such a scare with the London Blue Topaz then? Apparently the Geiger counter went off the scale? Are they now using a different type of irradiation (such as the one you mention) and the "old" method has been discontinued?

By the way, I have a "Hiddenite" that faded over a matter of weeks to an almost colourless stone! Is there anything that can be done to restore it or give it a bit more colour - that won't irradiate me!? Would heating do anything such as turn it into a Kunzite?

 

[Lee Little]

Your biggest danger with an irradiated gemstone is not the radiation, but color fading.

Some irradiated gems lose color when exposed to strong light or to heat.
Since irradiation is so hard to detect, the home brew method among some Thai gem dealers is to put suspect specimens in the strong Thai sun for a couple of days to see if they fade.

You know, MoreCarats, I think I have such stones and I think I have once posted the story about them as a question. They were bought by my father in 1977 I think in Laos. Three huge beautiful stones changing colors from amazing grape-purple to blue in daylight. Sold, of course, as alexandrites. None of us, of course, had seen a live alexandrite so everyone was happy. So they were made into earrings and a ring, my mom wore them, as later did I. Then I moved here and it took me a while to get them. To make a long story short, the color change almost disappeared with time. Now they look as not too saturated, lavender-violet amethysts. I am not wearing them any longer.

I thought it was a certain synthetic that faded with time but now I think they have been irradiated. I do not know about the techniques used in 1977 but I bet irradiation was one of the simplest ways to achieve desired effect.

Hi Crasru,
I would guess your 'Alexandrites' were actually Vanadium-doped Synthetic Sapphires. Best regards, Lee

 

[Arkteia]

Would they change color? And would the effect fade with time?
Also, if these are synthetic sapphires, I should expect to see curved growth lines, shouln't I?

 

[innerkitten]

Unless I had positive proof it was safe I would not feel right about having anything that had been nuked near my skin. I love the look of blue topaz but have always avoided them.
But thats just me.

 

[Lee Little]

It would be possible to see the curved growth lines in the right light with a microscope, sometimes even with just a 10x loupe but they are rarely ever easy to find. Fields of tiny bubbles are often easier to spot but they are not always present.
I have never read that the color of Vanadium treated Sapphire will fade but I have seen some old ones that were certified as such that had no color change, only a slight shift but perhaps they were duds to begin with.
Easiest would be to throw one on the refractometer and see if they are Sapphires or not. If they are indeed Sapphires then there would be only one possibility as far as I know and that would be Vanadium treated Sapphire.
The biggest clue was your description of grape purple to blue sold as Alex, that usually says Vanadium treated Sapphire.
Does anybody here know for sure if those type treated stones fade over time? I am thinking they do but have never seen much written on them. Best regards, Lee

 

[LD]

I've seen quite a number and none have faded. It's reasonably easy to test. Here's some info:

"Most gemstones described as synthetic alexandrite are actually synthetic corundum laced with vanadium to produce the color change. This alexandrite like sapphire material has been around for almost 100 years. The material shows a characteristic purple-mauve colour change which although attractive, it doesn´t really look like alexandrite because there is never any green. The stones will be very clean and may be available in large sizes. Gemological testing will reveal a refractive index of 1.759 - 1.778 (corundum) instead of 1.741 - 1.760 (chrysoberyl). Under magnification, gas bubbles and curved stria may be evident. When examined with a spectroscope a strong vanadium absorption line at 475 nm will be apparent." David Weinberg

 

[digitaldevo]

Originally the topaz was being nuked with bad radiation that had a very long halflife. Cobalt-60 irradiation has no real halflife as it leaves nothing harmful behind. They use it on food, mail sometimes I believe, to sterilize surgical tools and such. I've tested with Geiger and nothing.

As for the spodumene to restore the green it would take more irradiation. But you should be able to bring back the pink color by heating it to 200C using a step process to get there. I don't know off hand the amount of time at the 200C temperature it take to return pink though. Sorry.

As for Cobalt-60 irradiation, most red and rubelite tourmaline from Brazil and Afghanistan is treated with this method. Medium to dark pink from Afghanistan are all treated with this method. Many bi-color yellow-green out of Brazil are treated this way. They can even create watermelon tourmaline via this method. They even do so to many lighter blues from Brazil and Afghanistan to get those real nice indicolites.

No method to tell currently. Sometimes one can fine traces of heat but that does not assure cobalt-60 by any means.

In tourmaline the colors are permanent due to being annealed with heat afterward.

Completely safe treatment with no residual radiation like normal methods. Most everyone reading this has probably eaten plenty of cobalt-60 irradiated foods by now.