Joined: Tue Aug 01, 2006 3:24 am Posts: 4997 Location: McDonough GA
Well, Heliodor is not being irradiated, but goshenite is being irradiated into Heliodor. There is no method to detect this treatment. However, all that I have seen are a very bright canary yellow. If it's bright yellow and cheap you can be assured it's been treated.
Joined: Sat Jul 11, 2009 10:29 am Posts: 928 Location: USA
Jason wrote:
Well, Heliodor is not being irradiated, but goshenite is being irradiated into Heliodor. There is no method to detect this treatment. However, all that I have seen are a very bright canary yellow. If it's bright yellow and cheap you can be assured it's been treated.
Jason
Exactly. The method used, I believe, is Cobalt-60 Irradiation, and as Jason ahs stated, it can not be detected that I am aware of. But, again, as Jason stated, if it is super bright and super cheap, it is irradiated more then likely, lol.
Joined: Wed Jan 23, 2013 5:29 pm Posts: 1047 Location: Paris
Hello, this is Isabelle from France, newbie here. I have just found this old post which interests me. I have recently acquired a nice big, bright yellow heliodor. This stone is included with many elongated negative channels and other basal confetti-like cleavages, rather typical of heliodor I would say. I was wondering if it was likely that this stone could have been an irradiated goshenite ? Wouldn't people rather pick up non-included goshenite when they intend to treat it ? I suppose there must be big amounts of cheap, loupeclean goshenite, which would give out better stones, commercially speaking ? Thanks for your opinion.
(not just goshenite, but aquamarine as well, I think? Though of course they'd focus on cheaper pale stuff, I guess?) I have several crystals of this material--the color seems to be pretty uniform and distinctive across the ones I've seen. It's... *very* yellow. The process doesn't appear to be restricted to high quality pieces by any means--the ones I've had are average to decent crystal specimens, probably made from medium-quality pale aquamarine/goshenite from Pakistan.
Joined: Wed Jan 23, 2013 5:29 pm Posts: 1047 Location: Paris
Where would it be possible to see pictures of this typical bright yellow colour ? Compared to that of natural heliodor. Just to get a more accurate idea of the thing...
I definitely don't have a wide enough sample to say how useful this is, but this would be a typical color:
http://i.imgur.com/RnF3JBi.jpg I agree with Barbra, one shouldn't necessarily rely on this, but all the ones I have purchased have been essentially this hue, sometimes less intense. I'm not quite sure how to describe it; it's not quite what I'd think of as canary (maybe because it leans just a bit towards orange?) but others might disagree. Anyway, if you pair this hue with low price and uniformity across multiple pieces, I think you can reasonably assume irradiation, especially if they say they're from Vietnam or Tajikistan. The natural heliodor I've seen tends to be paler, and often has green overtones, but that's a limited sample. I definitely can't say that irradiation couldn't produce those paler hues, or that natural heliodor doesn't exist in the very yellow colors (I bet it does).
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
Isi, here is some material which has NOT been treated:
Further details G&G, Summer 2007, p 169
Further details G&G Winter 2010, p 312
Further details G&G, Summer 84 p 98
Summer'84 p99 wrote:
HELIODOR(GOLDEN OR YELLOW BERYL) Top-quality golden or yellow beryl is much rarer than aquamarine, although the best heliodor is not as valuable as the best aquamarine. Some yellow and golden beryls, when heat treated for 1-12 hours to between 280° and 600° (dependingon the source of the material and the inclusions), will turn a pleasing, more salable aquamarine color (no greater in intensity than the original yellow or gold);others, however, will just become a lighter yellow. Still others may also turn such a pale blue that they are worth much more left as heliodor. One can be sure that the best golden or yellow stones offered for sale have not been heat treated-but that others from the same crystal were undoubtedly tested.
Further details G&G Spring 96 p 53-54
Therefore, to speculate as to whether yellow beryl has been treated based on the color of the material may prove quite foolish.
@Barbra: It would not surprise me if that last beryl listed as being from Tajikistan actually is irradiated, and I strongly suspect the 'southeast Asian' ones as well. I can't check the reference on the Tajik one, but the 2010 paper about the southeast asian stones doesn't say that they're untreated, only that they had appeared on the market in Vietnam and that one buyer suspected they were from Cambodia. The conclusion that seems to have been drawn since is that these are in fact artificially irradiated pale Vietnamese aquamarine. See the more recent Nguy Tuyet Nhung, et al. "Gemstones From Vietnam: An Update." Gems & Gemology 48.3 (2012): 158-176. The picture on page 170 shows crystals with this same distinctive color and describes them as irradiated. The article about the Tajik beryl is from '96, and the consensus seems to have since settled on there being no natural source of yellow beryl in Tajikistan (though I would be happy to be proven wrong on that). I will emphasize I can't cite a literature source for this one, though.
Anyway, despite that I definitely agree (especially in light of the photos) that one shouldn't try to judge irradiation status just from the color. If a gemologist can't yet do it with a microscope and advanced instruments, a glance probably won't cut it either. I can say I'm pretty sure about the most recent ones I got for three reasons besides color: 1) they were listed as coming from Afghanistan (not famous for its production of yellow beryl) by a seller with plenty of other irradiated stones with varying levels of disclosure. (Irradiation is logistically easy for these goods since there's a facility in Lahore). 2) they look exactly like Pakistan aquamarine, which he also sells, except all the same shade of yellow. 3) perhaps most importantly, I got 7 nice crystals for 10 dollars.
@Isi: what does this mean for your stone in particular? I don't know. It depends who you bought it from, where they said it was from and how much you paid.
Joined: Wed Jan 23, 2013 5:29 pm Posts: 1047 Location: Paris
Well, I bought it from a friend, a graduate gemologist who recently turned into a gemstone seller. I definitely trust him. He told me he bought the stone in Bangkok but didn't ask about the origin. I bought the stone for about 400 dollars, it's a nearly 14 carats piece, nicely cut. He told me the price was low because the stone is included and besides, in France, there is no demand for heliodor (that at least is true !)
This is because I suspected that something might have happened to this stone that I began my search on internet. Didn't find much though, except this post.
I'll post a picture next week anyway. Even if I understand that the colour doesn't mean much, I find my stone is closer to the pictures of Scarodactyl than to the ones of Barbra. A pity that even labs cannot detect the treatment, otherwise I would gladfully have had it tested, for science's and my curiosity's sake.
Joined: Sun Oct 16, 2005 12:22 pm Posts: 21602 Location: San Francisco
I agree with you Isi (and Scarodactyl)....I wish there was something definitive.
Maybe I'll call GIA on Monday and see if they have any updates. I have every G&G from 1981 and I checked for all info about yellow beryl. Interesting I could find no info withing G&G refuting their original article on Tajikistan....BUT there is a lot of online speculation about the material being subjected to irradiation.
Users browsing this forum: No registered users and 13 guests
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot post attachments in this forum