Blue fluorescence in an Unheated "Velvet Blue" Sapphire from Sri Lanka (365nm LWUV)

[Dr_Diesel]

Well this is just freaky!

Has anyone ever heard of Blue fluorescence in a Blue Sapphire?????​

So, I fumbled my beautifully organized "box of rocks" and CLUNK, CRACKLE PSHHHH! 15 gems scattered across my desk and wood floor.

Nice one! Clutz.

Several of the stones were fluorescent, so I turned the lights off and brought out my 365nm LWUV torch. I managed to find them all pretty easily....but two things were unexpected:

1) Some of my Gray Burma Spinel showed weak red fluorescence. Maybe not a surprise since they are likely from Mogok where trivalent chromium is plentiful.

BUT THEN...​

2) I saw a weak/moderate blue fluorescence illuminating a stone that was precisely the size and shape of my little unheated "Velvet Blue" unheated sapphire. I turned on the lights and sure enough!

I Googled this phenomenon and found nothing. Only an article on chalky, uneven SWUV blue fluorescence in heated sapphire, but the lab certificate and clear presence of rutile silk rules that out.

I tried to search for blue fluorescence caused by rutile and again, nothing.

I thought maybe rutile was just scattering light across the stone and made it "seem" to glow. Nope. It was a different color. It was the color of the blue fluorescence that we see in diamond. Moreover it is perfectly even throughout the stone and not chalky in appearance. If the stone were heat treated with boron, it would likely get into cracks and show a streaky appearance. I'm baffled.

I mean, I always thought this stone "glowed" in natural light, but blue fluorescence wa about the last thing on my mind.

HAS ANYONE EVER HEARD OF THIS BEFORE????
Is this some sort of bizarre unicorn, or is there something else going on here?
Please tag anyone who might be in the know. @landscape perhaps? @Karl_K ? What the heck is this???
​

***There is an article about hydrothermal synthetic sapphire showing moderate chalky green fluorescence under LWUV, but this is blue. Like boron blue. I also don't see the growth patterns that they describe in the article. Could the lab (LGL London Gem Lab in Sri Lanka) have been wrong? I am grasping at straws, as I can't make head or tails of this.

https://git.or.th/upload/is_art/file/file-789-Thai-776812639.pdf

Anyway, I'll let the photos speak:

 

[mellowyellowgirl]

Very cool and that’s a beautiful sapphire!!!

 

[Begonia]

Cool. Now tell is about that second smaller sapphire. She's a beaut.

 

[Dr_Diesel]

Cool. Now tell is about that second smaller sapphire. She's a beaut.

The violet one just above the blue?

 

[Fax]

Oh! Now you got me going
I checked some of my stones and found a light blue sapphire that seems to fluorescence (my up lamp is not the best).

Sorry for the bad photo (just wanted to show you quickly).

 

[Begonia]

The violet one just above the blue?

The one above the red spinel
Miss Emerald Cut.

 

[Rfisher]

Do you have any diamonds with blue fluorescence you can photo next to your blue sapphire? To see the comparison?

For science and all

 

[Dr_Diesel]

The one above the red spinel
Miss Emerald Cut.

Oh!

I think that’s the one we are discussing! The glowing blue radiant emerald cut above the small red spinel, correct? That one is a 1.26ct, unheated “velvet blue” sapphire from Sri Lanka.

Or are you referring to the bigger, Oval 2.98ct Pinkish-Purple sapphire that Jeff Davies cut (above the big red spinel)?

 

[Dr_Diesel]

Do you have any diamonds with blue fluorescence you can photo next to your blue sapphire? To see the comparison?

For science and all

Of course! I was thinking the same!

 

[Dr_Diesel]

Do you have any diamonds with blue fluorescence you can photo next to your blue sapphire? To see the comparison?

For science and all

… so now I can’t tell if the sapphire is actually fluorescing or if the silk is just scattering light from the UV torch.

What do you think?




For clarification, here are the 4 diamonds that fluoresce blue (red circles), and this is light reflecting from the stones onto my desk (blue arrows).

 

[Dr_Diesel]

Oh!

I think that’s the one we are discussing! The glowing blue radiant emerald cut above the small red spinel, correct? That one is a 1.26ct, unheated “velvet blue” sapphire from Sri Lanka.

Or are you referring to the bigger, Oval 2.98ct Pinkish-Purple sapphire that Jeff Davies cut (above the big red spinel)?

The one above the red spinel
Miss Emerald Cut.

Here are some videos in daylight:

https://imgur.com/a/fLEPOKi

 

[ItsMainelyYou]

There is something terribly wrong. You must send it to me immediately.
For safety, of course. It's going to be okay, it's a sacrifice I'm willing to make.

* are we absolutely sure that's not a very fine cobalt spinel? They do that.

 

[Dr_Diesel]

There is something terribly wrong. You must send it to me immediately.
For safety, of course. It's going to be okay, it's a sacrifice I'm willing to make.

* are we absolutely sure that's not a very fine cobalt spinel? They do that.

Oh, THANK YOU!!!! Pleeeease take this off my hands!

I'm worried it may be radioactive!

The lab is pretty sure it's sapphire:

 

[ItsMainelyYou]

Oh, THANK YOU!!!! Pleeeease take this off my hands!

I'm worried it may be radioactive!

The lab is pretty sure it's sapphire:

I'm here to serve. Put it in the box, use the oven mitts.

 

[Dr_Diesel]

Apparently this is one sexy sapphire! ​

I just clicked on the IMGUR link and got this message:

​

I promise, its just videos of the sapphire!



It's safe to click

 

[HockeyMama]

Well that is one sexy (I got the same message), beautiful, velvety blue sapphire. I'm in the US and would love to find a sapphire like this. What are the words you would use to describe it to a vendor? Would you ask BG Stones? Any chance this one will be offloaded in search of your ruby?

 

[Rfisher]

This probably won’t help you, @Dr_Diesel
(How intriguing tho!)
Mine looks somewhat to yours similar on photo, but not to naked eye. On a much smaller scale w/no pedigree tho
And most likely due to my horrific photo taking abilities


But I’m curious now, so….
@mpc
@Sparklemore

What do your Madagascar unheated blues do under LW UV?

 

[Karl_K]

@Karl_K ? What the heck is this???
​

Waykewliwantitusness

 

[Cerulean]

I wonder if it’s really blue flour or some other factor like you’re hypothesizing. Really interesting either way

Basically, I wonder if it’s an optical effect. Is there such a thing as white flour? I ask bc I wonder if it’s the eye just perceiving blue due to an optical effect. As different wavelengths of light are refracted (they are bent), then pass thru the eye at different rates. Blue happens to have the shortest wavelength and is refracted more, so can be more pronounced compared to longer wavelengths like red. This is called chromatic aberration. Not sure if it’s relevant here but I wonder?

 

[Rfisher]

Not definitive, but here’s my photo.
Never have considered my sapphire as fluorescent - I think I ‘see’ the silk as doing something via naked eye, but not fluorescent. As Cerulean is saying - I think.


Again, I’m not who DrD is asking as an expert - nor do I see in person exactly what my photo depicts. And he I can only assume likely is having a different experience with his stone - as I am with mine.


Interesting discussion tho!

 

[Starstruck8]

@LilAlex once mentioned a LWUV flashlight with an exceptional combination of bright UV and a built-in filter to block the visible blue.

I have always used a cheap little UV penlight that I got from Esslinger whenever I want to check for fluorescence in a colored stone. But I started reading a bit more and learned that the cheap ones are mostly ~ 395nm with tons of spillover into visible (violet) light. That's what mine was -- looked like a tiny, old-school "blacklight." There are much better ones that are mostly 365nm with a cutoff filter that eliminates almost all visible light. (Note that both 365nm and 395nm are "long wave" UV and the only thing I was interested in.)

So, based on lots of positive reviews on Amazon -- mostly from the dog urine, coolant leak, and yooperite crowd (!) -- I got the LIGHTFE UV301D. It uses a disposable AA battery although for a few bucks more there is the UV301A model powered by a rechargeable lithium battery. It was $31 but after letting it marinate in my cart for a while, I got a discount coupon so it was $28. It's tiny but feels well made with a machined aluminum case and push-button rubberized on/off on the back end.

Here it is next to my old standby and a quarter for scale:

It is amazingly bright. Practically zero visible light but the fluorescence off a piece of plain white paper in a dark room is almost blinding.

As a test case, here is a pendant that we got from Inken a while back -- a vivid unheated 2-ct-ish pink sapphire in a handmade platinum mounting. Excluding the bale, it's maybe 5/8" or ~ 15mm top to bottom. (And my wife absolutely loves it -- can't omit that fact -- my blah ambient-ceiling-light photos below showcase the center stone adequately but do not do justice to the "bling" factor of the double row of melee!)

All the following photos undersell the fluorescence with either of the UV lights although they are completely representative of the differences that the eye "sees." They were all shot in RAW with minimal post-processing (plus white-balance correction on the ambient-light ones) on a delayed shutter release at high ISO with a tripod-mounted macro lens and full-frame DSLR body.

Under ambient light:

With my trusty old UV penlight:

With the LIGHTFE UV301D:

Just so amazing to see the sapphire light up like a pink/red LED only 10X brighter -- and the cool and varied fluor in the diamond melee with the various blues and even an orange and a green. The tiny red "specks" must be secondary reflections of the bright red off the front surface of the lens "filter" and then off the shiny metal. Even the lint on the faux suede pouch behind the pendant lights up.

Maybe you could try with one of these, or something similar. Or maybe a gemmologist's 'official' viewing box, which would have a built-in filter. This might help to distinguish true fluorescence from scattering from silk.

 

[winnietucker]

Your sapphire is gorgeous. Have you got any plans to set it?

 

[Dr_Diesel]

Well that is one sexy (I got the same message), beautiful, velvety blue sapphire. I'm in the US and would love to find a sapphire like this. What are the words you would use to describe it to a vendor? Would you ask BG Stones? Any chance this one will be offloaded in search of your ruby?

This one is typically called “Velvet Blue.” The colors is often compared to milk of magnesia bottles


Here’s a page from Lotus Gemology that describes different trade colors. Mine was certified in Sri Lanka by London Gem Lab and they seem to use similar standards and terminology.

Color Types

Ruby & sapphire color types used on Lotus Gemology reports, including Pigeon's Blood, Royal Blue, Cornflower Blue, Padparadscha, and others.

lotusgemology.com

In my experience, Lotus is remarkably consistent with their color grading.

If you buy from a Thai seller, just ask them to get a Lotus certificate. If it says velvet blue, it should look like the one we are discussing.


Similarly, if you buy from a Sri Lankan seller, ask for an LGL certificate.

Regarding consistency of color grading, I have two stones that Lotus certified as “intense cornflower blue” and a recent saw another one with the same certification. The color is almost identical in all 3 stones. It is shockingly consistent.

“Intense Cornflower Blue” looks like this:



Now, in terms of finding these stones, that’s tricky. It’s a very rare comment to see - and a very rare appearance.

… and with that in mind, I’m very unlikely to let go of this one anytime soon.

BG Stoned may be able to hunt one down for you, but their prices tend to be extremely high.

I’ve also been to their shop before and they have what I refer to as “magic lighting.” I teased one of the owners about it and he laughed. Stones that look incredible under their lighting never look quite as good anywhere else.

I’ve brought boxes of my own stones in there and. suddenly, pieces that I thought were quite mediocre become top-tier gems .

I think well of the shop and the lighting is not an attempt to deceive. They just show their goods under the best possible lighting conditions.

So the takeaway is that, if you do buy from them, make sure you get photos and videos, outdoors in natural lighting…. And definitely bargain with them!

 

[Dr_Diesel]

This probably won’t help you, @Dr_Diesel
(How intriguing tho!)
Mine looks somewhat to yours similar on photo, but not to naked eye. On a much smaller scale w/no pedigree tho
And most likely due to my horrific photo taking abilities


But I’m curious now, so….
@mpc
@Sparklemore

What do your Madagascar unheated blues do under LW UV?

Oooh! I didn’t even look at my Madagascar unheated blue under UV!

 

[Dr_Diesel]

@LilAlex once mentioned a LWUV flashlight with an exceptional combination of bright UV and a built-in filter to block the visible blue.



Maybe you could try with one of these, or something similar. Or maybe a gemmologist's 'official' viewing box, which would have a built-in filter. This might help to distinguish true fluorescence from scattering from silk.

@Rfisher @Cerulean

My UV torch has some spill over into visible light, obviously, but less than most UV flashlights.

In order to take a photograph, I have to use the perimeter of the light field, because the intensity seems to blow out my camera sensors when I shine it head on. The camera just picks up a big blur.

In that perimeter lighting however, there is definitely more spillover into visible light. The more I play with this, with the aid of everyone’s invaluable feedback, the more I think that this is just silk doing its thing with the visible blue light.

This one is perhaps the most compelling photo:



When I shine the light directly on the stones with red fluorescence and the diamonds with blue fluorescence, they light up like they’re going to catch fire.

The sapphire’s glow, on the other hand does not intensify. It maybe even weakens a bit - suggesting that is likely not true fluorescence.

 

[Dr_Diesel]

Your sapphire is gorgeous. Have you got any plans to set it?

No plans just yet. All of my funds (and efforts) are being corralled for the Mogok Ruby hunt, hence my progressive selling spree. The interesting thing is that I’m finding a number of super cool stones (different species) in the process of that hunt. I’ve seen a few that were awfully tempting, but I’m trying to stay on task!

 

[Bron357]

Oh, THANK YOU!!!! Pleeeease take this off my hands!

I'm worried it may be radioactive!

The lab is pretty sure it's sapphire:

Just so you know, I’m happy to offer my services as I’m a known “dealer” of bio hazards here in Aust, I think it would work well in my “other” watch conversion ha ha.

 

[Dr_Diesel]

I wonder if it’s really blue flour or some other factor like you’re hypothesizing. Really interesting either way

Basically, I wonder if it’s an optical effect. Is there such a thing as white flour? I ask bc I wonder if it’s the eye just perceiving blue due to an optical effect. As different wavelengths of light are refracted (they are bent), then pass thru the eye at different rates. Blue happens to have the shortest wavelength and is refracted more, so can be more pronounced compared to longer wavelengths like red. This is called chromatic aberration. Not sure if it’s relevant here but I wonder?

Here is, what I believe to be, good evidence to support your hypothesis:


Here we see visible blue light reflecting off of stones with red fluorescence onto my desktop. These reflections appear to be the same color and quality as the illumination we see in the sapphire.

I think this is reasonably good evidence that we are probably witnessing visible blue light reflecting and scattering throughout the silk network inside of the sapphire, yielding the glowing appearance.

This is not unlike what happens with this stone on overcast days or in other kinds of diffuse lighting.

The light seems to scatter throughout the crystal and return to the eye as a diffuse blue glow (rather than as distinctly “lit up” facets & virtual facets next to contrasting darker areas as we see in very clear, crystalline material).

Under a cloudy blue sky, the body color is even more intense than the color it displays in indoor lighting. I presume the color is further amplified by reflecting the color of the sky.

 

[mellowyellowgirl]

@Dr_Diesel I really like Lotus’s grades for blue sapphires and find them very accurate so it’s encouraging to hear you bring them up.

What I’ve found super helpful is that sometimes when a vendor posts very flattering videos but also a Lotus report and Lotus's does not give them a cornflower designation even though the video looks amazing, I know that ain’t the sapphire for me.

I am kicking myself for losing out on a peacock blue though. It was heated, I quibbled and I may just never get over it!

PS have you seen many indigo or twilight ones? Based on what I’ve seen of the sample pictures on their website I don’t think it is for me! Seems to be that steely blue I dread.

 

[Dr_Diesel]

@Dr_Diesel I really like Lotus’s grades for blue sapphires and find them very accurate so it’s encouraging to hear you bring them up.

What I’ve found super helpful is that sometimes when a vendor posts very flattering videos but also a Lotus report and Lotus's does not give them a cornflower designation even though the video looks amazing, I know that ain’t the sapphire for me.

I am kicking myself for losing out on a peacock blue though. It was heated, I quibbled and I may just never get over it!

PS have you seen many indigo or twilight ones? Based on what I’ve seen of the sample pictures on their website I don’t think it is for me! Seems to be that steely blue I dread.

I don't look at the indigos or twillight blues long enough to even get to the certificate. Moreover, most people will get a $15 verbal report from the lab before certification if they are afraid one of those "damning" terms might get published on a certificate.

Regarding cornflower blues, look specifically for the modifier "Intense" Cornflower Blue. It's a somewhat rare comment, but it makes all the difference!

Here's an example of certificate:

Page 1 shows:

Color (Daylight): Blue​

Saturation: Intense​

Tone: Medium​

Page 2 shows:

COLOR TYPE: Cornflower Blue​

​

​

As for the peacock blue, I feel your pain. I recently opted out of one as well due to an eye-visible inclusion and overly-deep, narrow cutting. I don't regret it, but that color is both spectacular and super rare.