"AGL Discovers Heated Sapphires with Unstable Color Centers"

[Rad_Fan]

Received this newsletter from AGL today and wanted to share. I know that many members are in searching of or interested in padparadscha and this could be useful.

Here is the PDF of the entire press release.

 

[elle_71125]

Thanks @Rad_Fan . That’s an interesting update.
Adding it in picture form just in case it’s easier for anybody.

 

[icy_jade]

Thanks for sharing.

I actually recall my jeweller mentioning that yellows and pads are generally not color stable. Seems like a known thing in trade? Does anyone know?

 

[Rfisher]

Thanks for sharing.

I actually recall my jeweller mentioning that yellows and pads are generally not color stable. Seems like a known thing in trade? Does anyone know?

I would take that to mean the jeweler knew those stones he’s talking about are non-stable treated.
The fading is not a thing with natural colored stones, right?!?

 

[icy_jade]

I would take that to mean the jeweler knew those stones he’s talking about are non-stable treated.
The fading is not a thing with natural colored stones, right?!?

Natural. He wasn’t referring to treated. He mentioned it fairly casually like it’s a well known thing. The conversation actually started with me asking about unstable yellows (not heated) that faded after being kept in safe that I’d heard from another jeweller, and then he mentioned that pads colors can also fade if you keep in safe. But just need to wear under sun periodically and the color will return.

 

[Rfisher]

Well I guess fading and returning is different than fading forever or color changing forever.
Still - eek!

 

[elle_71125]

I hate the thought of spending oodles of money on a gorgeous gem only to find that the color fades out after a year or so.

 

[icy_jade]

@Rfisher @elle_71125 I know right? I was like - but pads are soooo expensive??? But he just shrugged and said it’s common.

You can do a color stability test at most labs I think. My yellow sapphire was assessed for color stability at two labs and I wouldn’t have bought if it wasn’t certified.

 

[Rad_Fan]

Reading your posts have me

 

[Shijitake]

I just bought a pad last year and a pink recently :/

 

[Mrs_Strizzle]

I am absolutely stunned that not only does this seem to be true, but that this is either news to the AGL, or they just figured out they can charge us more to determine this.

 

[Rad_Fan]

I am absolutely stunned that not only does this seem to be true, but that this is either news to the AGL, or they just figured out they can charge us more to determine this.

I am actually wondering that also, especially when they mentioned about $50 fee at the end.

 

[PieAreSquared]

The "Release" from AGL looks like a giant infomercial to me -"Be afraid, and send us another $50 or else the standard report we just charged you for is worthless'.

After reading this post, I kept thinking I had already heard about this somewhere else a while ago...

Sure enough, the unstable color of some orangey-pink sapphires was reported at least a year before AGL's amazing "discovery", and confirmed by the truly world-renowned Swiss Gemmological Institute SSEF.
The 'tenebrescence' or reversible photochromism, of some yellow sapphires was reported by the same institute way back in 1997...

If you really want to geek out, read the original article here:
https://gem-a.com/images/JoG/JoG2018_36_4.pdf

 

[icy_jade]

Yeah cos other labs don’t seem to charge more for what is a relatively simple test?

GIT examples:

 

[mellowyellowgirl]

I hate the thought of spending oodles of money on a gorgeous gem only to find that the color fades out after a year or so.

hehe might as well spend a few hundred bucks on a kunzite!

 

[voce]

I wonder if this same problem affects pad spinel. There are no yellow spinels, but plenty of pink and orange and orangey-pink.

 

[MissyBeaucoup]

Brad at the Gem Trader occasionally has some hackmanite for sale. This is a stone that is collectible partly because it has such strong tenebrescence. If anybody has some, please post pictures.

This is a photo of Brad’s that I saved. It shows hackmanite before, during, and after exposure to SWUV light. (I would have bought it but I only have a LWUV light. You do need eye protection to use SWUV, but that’s a good point that it could be contained in sunlight.)

Anyway, tenebrescence is super cool! I understand someone being disappointed if their sapphire turned a less pretty color though.

 

[icy_jade]

Brad at the Gem Trader occasionally has some hackmanite for sale. This is a stone that is collectible partly because it has such strong tenebrescence. If anybody has some, please post pictures.

This is a photo of Brad’s that I saved. It shows hackmanite before, during, and after exposure to SWUV light. (I would have bought it but I only have a LWUV light. You do need eye protection to use SWUV, but that’s a good point that it could be contained in sunlight.)

Anyway, tenebrescence is super cool! I understand someone being disappointed if their sapphire turned a less pretty color though.

Here you go. Not mine but came across them some time ago and found it quite interesting as well. Beautiful color change

https://global.rakuten.com/en/store/jewelclimb/item/1038940/

And

https://global.rakuten.com/en/store/jewelclimb/item/1049217/

 

[MissyBeaucoup]

@icy_jade

Those are beautiful hackmanite stones! Thanks for sharing!

 

[Anne111]

Now I'm totally confused. Does this mean we can now buy only completely unheated stones to be 100% sure they are really untreated, except oiling? WT... is going on???

This whole treatment issue is driving me nuts!!!!!!!!!!!!!!!!!!!

Could we start a list with vendors who sell only gems whose treatment-statement can be trusted based on the type of lab reports they provide?

Aside the 'recommended vendor list':
'Recommended vendors with verified or correctly disclosed treatments'? or something of the kind?
That would thin the currently too long list and give those who care about treatments a better place to start.

A sample of somebody NOT on that list would be a new UK-Indian website with hundreds of interesting sapphires/rubies whom I asked to tell me about the treatment of a specific gem (they didn't give any data in their online presentation at all, only "Grade AA") and the answer was.... 'silence'. How can we be expected to buy from anybody if the value of a sapphire/ruby etc. could be $100 or $1000 depending on treatments which we cannot know in te end?

 

[icy_jade]

Now I'm totally confused. Does this mean we can now buy only completely unheated stones to be 100% sure they are really untreated, except oiling? WT... is going on???

This whole treatment issue is driving me nuts!!!!!!!!!!!!!!!!!!!

Could we start a list with vendors who sell only gems whose treatment-statement can be trusted based on the type of lab reports they provide?

Aside the 'recommended vendor list':
'Recommended vendors with verified or correctly disclosed treatments'? or something of the kind?
That would thin the currently too long list and give those who care about treatments a better place to start.

A sample of somebody NOT on that list would be a new UK-Indian website with hundreds of interesting sapphires/rubies whom I asked to tell me about the treatment of a specific gem (they didn't give any data in their online presentation at all, only "Grade AA") and the answer was.... 'silence'. How can we be expected to buy from anybody if the value of a sapphire/ruby etc. could be $100 or $1000 depending on treatments which we cannot know in te end?

Huh? As far as I understand, untreated yellow and pad sapphires can also have unstable colors, just like heated ones. Key is to check for color stability.

Buying from the trusted vendor list doesn’t guarantee you get a color stable stone as far as I’m aware. Get a decent lab to certify the stone before you buy. The color stability test doesn’t require expensive fancy equipment but does run the risk of an unstable stone changing color so if a vendor isn’t willing to get the test done, I’ll be wary too.

 

[Anne111]

is that so? What makes them unstable?

 

[voce]

is that so? What makes them unstable?

Interactions between UV spectrum photons and the band gap potential of electrons in elements within the crystal structure of the sapphire. It probably requires understanding of materials science to really understand this.

As far back as 1987, there were seven types of yellow sapphires identified, each with a different color center. See this article from Gems and Gemology, Winter 1987.

I also came across this article from James Allen and thought it interesting and much less technical.

 

[icy_jade]

is that so? What makes them unstable?

Natural for some of them, and reversible too unlike the irradiated ones...


And these are easy to read too:

Buying Srilankan Yellow Sapphires? We've got some interesting facts

Key tips to note when buying Srilankan Yellow Sapphires, the beautiful gems that might surprise you, but are essential to know.

www.thegemstonequeen.com

https://www.ssef.ch/wp-content/uploads/2018/03/2018_Padparadscha_colour_stability_facette.pdf

 

[Anne111]

Thanks. Just to be clear: An unheated padparadscha or yellow sapphire would come up as 'color unstable' in a standard testing process at the high-end labs?

 

[icy_jade]

Thanks. Just to be clear: An unheated padparadscha or yellow sapphire would come up as 'color unstable' in a standard testing process at the high-end labs?

Possible but not always. There are color stable pads and yellow sapphires just as there are non-color stable ones. So best to check if you are in the market for a pad or yellow sapphire. If you get from a reputable vendor he/she should know. If not then ask for a cert from a decent lab that has/will perform the color stability test

 

[ChaiK]

Possible but not always. There are color stable pads and yellow sapphires just as there are non-color stable ones. So best to check if you are in the market for a pad or yellow sapphire. If you get from a reputable vendor he/she should know. If not then ask for a cert from a decent lab that has/will perform the color stability test

Or a pink sapphire. Testing is good.

 

[kindred]

I can't figure out how to quote, but I have the same question as @voce. I am about to buy a pink/red/orange spinel and before I spend thousands of dollars on one I'd like to know if spinels can have the same problem.