Phosphorescence in Diamonds-Study, and a request for sharing information

[Sithathoriunet]

As from what I have experienced playing around: stones with a very strong fluorescence also tend to phosphorescence. Mine - with super strong blue fluorescence - does so very clearly and for quite a bit but I’ve never heard of 10 hours! (That is so cool! My other stone with medium fluorescence also shows the effect but much less.

Phosphorescence

I stumbled over this topic because Nikki1415 mentioned it in relation to her gorgeous OEC target ring. I have heard of fluorescence but not phosphorescence before. Doing a bit of research I came across this article about the (blue) Hope diamond...

www.pricescope.com

Hi Roselina
Do you have any pictures of your gems, I would love to see them "in action"!
I also checked out the thread you mentioned, very interesting ...this subject. Maybe we can get some data on what people are seeing with the phenomena and how long we can get it to last, if we can influence this and how...

 

[Demon]

I have asked a few questions about all this of two of my learned friends who are experts in this field. Will report back.
"
Dear John and Grant,
Short wave creates stronger phosphorescence. Correct?
Does the length of SW excitation time Phosphorescence lasts?
Or is it purely the strength of the SW source?
Or something else like the number of dislocations etc?

Garry - could you also ask them if the strength and color of fluorescence matters? I seem to recall reading somewhere that only strong blue fluorescent stones will phosphoresce, but I'd like to know for sure. (I have a fancy green yellow that phosphoresces and it has strong blue fluorescence) Thanks.

 

[Garry H (Cut Nut)]

Oh my goodness thank you for that! I can't wait to hear what they have to say on the subject

This is a quote from John Chapman. John was for many years the senior scientist working for Argyle Diamonds and has recently teamed up with another friend Branko Deljanin to run gem conferences, and they specialize in teaching gemologists the identification of natural and synthetic diamonds and diamond treatments. John makes equipment that we use in our stores to ID diamonds.
"Generally SW seems to be more effective than LW, I guess because the higher photon energy will elevate any electrons to at least the LW level.
The duration of excitation will have a diminishing effect on the intensity and hence duration of the phos. So exposure longer than say 15 secs will in many instances produce no increase in either the intensity or duration of the phosphorescence.
The strength of the SW source coupled with the concentration of reactive defects will determine the intensity of the fluorescence after which the decay will follow an exponential form with a constant half-life for a given defect.
There are many images of fluorescence and phosphorescence on the instagram account @gemetrixproducts"

 

[Roselina]

Hi Roselina
Do you have any pictures of your gems, I would love to see them "in action"!
I also checked out the thread you mentioned, very interesting ...this subject. Maybe we can get some data on what people are seeing with the phenomena and how long we can get it to last, if we can influence this and how...

Seems like the longer I shine the torch on it, the stronger it glows. Here it was about 20 seconds.

 

[Sithathoriunet]

This is a quote from John Chapman. John was for many years the senior scientist working for Argyle Diamonds and has recently teamed up with another friend Branko Deljanin to run gem conferences, and they specialize in teaching gemologists the identification of natural and synthetic diamonds and diamond treatments. John makes equipment that we use in our stores to ID diamonds.
"Generally SW seems to be more effective than LW, I guess because the higher photon energy will elevate any electrons to at least the LW level.
The duration of excitation will have a diminishing effect on the intensity and hence duration of the phos. So exposure longer than say 15 secs will in many instances produce no increase in either the intensity or duration of the phosphorescence.
The strength of the SW source coupled with the concentration of reactive defects will determine the intensity of the fluorescence after which the decay will follow an exponential form with a constant half-life for a given defect.
There are many images of fluorescence and phosphorescence on the instagram account @gemetrixproducts"

Thank you Gerry! This is getting very interesting, I am wondering how many fancy white diamonds have been tested, I almost want to say that perhaps they have the ability to phosphoresce longer because of significant imperfections? Those microscopic needle like inclusions that give them the white-ness?
I wish I had the funds to purchase a few more whites just to test them...

 

[Sithathoriunet]

Seems like the longer I shine the torch on it, the stronger it glows. Here it was about 20 seconds.

Gorgeous!!! Wow!! I love your ring, and your diamond as well! That looks bright for phosphorescence, did it also glow longer? Or only brighter?

 

[Roselina]

Gorgeous!!! Wow!! I love your ring, and your diamond as well! That looks bright for phosphorescence, did it also glow longer? Or only brighter?

Brighter and longer - I’ll test again and will come back with the results. The stone is older, but not OEC, very shallow and has a horrible cut by PS standards. But I love it dearly and would never trade it, also because of it‘s hidden superpower! Which I knew nothing about when we bought it second hand and discovered by accident.

 

[Sithathoriunet]

Brighter and longer - I’ll test again and will come back with the results. The stone is older, but not OEC, very shallow and has a horrible cut by PS standards. But I love it dearly and would never trade it, also because of it‘s hidden superpower! Which I knew nothing about when we bought it second hand and discovered by accident.

I am sooooooo excited to hear your results!!! I can imagine it was a very happy accidental discovery! I knew nothing of the abilities of my diamond either, I feel like a child just finding out it is a magic gem!

 

[Sithathoriunet]

I have found some interesting pieces on fluorescence and phosphorescence in diamonds, this short one is interesting and mentions that, "In most cases, the fluorescence is brightest under long wave (365nm)" which is the case with my diamond...

Diamonds

Approximately 30% of all diamonds show a fluorescent response under UV. In most cases, the fluorescence is brightest under long wave (365nm). The fluorescent response is activated by a complex interplay between various types of defects in the crystal structure of the diamond, the two most...

www.naturesrainbows.com

Here are some pictures of these little lights showing what they can do!

 

[Sithathoriunet]

This little article is very cool and it even has a beautiful chart you can download in pdf for that shows diamonds and their expected reactions to uv;

Gemetrix Products - Gemetrix Pty Ltd

www.gemetrix.com.au

I tried to upload it here for everyone, but its a pdf so it doesn't want to work..apologies for that...
But, again, it mentions all colors and types of diamond, but no mention of fancy white diamonds...Still, it is very neat to look through...

 

[Sithathoriunet]

ok, I may have figured out how to attach the chart..I don't know how big this will come out...giving it a try.

 

[Sithathoriunet]

This is a study on the effect of phosphorescence in diamonds done in 1946..long read, but I think I may be a nerd or something because I love this stuff.

https://www.ias.ac.in/article/fulltext/seca/024/01/0182-0186

 

[Sithathoriunet]

The colored diamonds in the Aurora Butterfly of Peace were assembled over a 12-year period by Alan Bronstein and Harry Rodman of Aurora Gems Inc., New York. Shown here in long-wave UV radiation. Photo by Robert Weldon.

 

[silkystarlight]

I have found some interesting pieces on fluorescence and phosphorescence in diamonds, this short one is interesting and mentions that, "In most cases, the fluorescence is brightest under long wave (365nm)" which is the case with my diamond...

Diamonds

Approximately 30% of all diamonds show a fluorescent response under UV. In most cases, the fluorescence is brightest under long wave (365nm). The fluorescent response is activated by a complex interplay between various types of defects in the crystal structure of the diamond, the two most...

www.naturesrainbows.com

Here are some pictures of these little lights showing what they can do!

OMG, I am absolutely FLOORED by the glowing going on here!! Thank you for sharing all of that info... I am definitely going to poke through some of those articles when I have some free time!

All I have to say is, this thread has made me want to seek out my very own little glowing diamond.... time to add that to the list of future projects!

 

[Sithathoriunet]

OMG, I am absolutely FLOORED by the glowing going on here!! Thank you for sharing all of that info... I am definitely going to poke through some of those articles when I have some free time!

All I have to say is, this thread has made me want to seek out my very own little glowing diamond.... time to add that to the list of future projects!

Yes!!! The more magic gems the better!

 

[Sithathoriunet]

The Foxfire diamond is the largest known uncut, gem-quality diamond mined in North America. “The Foxfire is truly exceptional, one of the great treasures of the Earth,” said Jeffrey Post There is an info article here;

The Foxfire Diamond, Revisited | Gems & Gemology

The 187.63 ct rough diamond from Canada’s Diavik mine shows surprising reactions to ultraviolet light.

www.gia.edu

It is capable of both fluorescence and phosphorescence, neat!

 

[Roselina]

Such cool info! Thanks!
With my normal UV torch it glows longer when the stone was equally exposed longer to the light. Maybe also a bit brighter but not much. 3 min of UV around 5 min of glow in the dark.

 

[Sithathoriunet]

Such cool info! Thanks!
With my normal UV torch it glows longer when the stone was equally exposed longer to the light. Maybe also a bit brighter but not much. 3 min of UV around 5 min of glow in the dark.

This was my finding, I get roughly 10 hours of glow charge per 1 hour of SW UV exposure, I have tried to charge it for longer but the glow time seems to be maxed out at 10 hours or so..they seem to act almost like rechargeable batteries that have a charge max and a last max..lol But of course way better because they are gems and natural...lol
This subject is fun, maybe I should have called it night light diamonds, or magic gems...

 

[Garry H (Cut Nut)]

You are having fun!
FYI - long wave and short wave UV used by gemologists and mineralogists are based on the fact that the only wavelengths we were capable of generating in 'black light' were based on mercury fluorescent tubes and certain filters.
TWO PROBLEMS:
1. the frequencies are all over the place - there is a GIA 2013 study in G&G that explains the issues.
2. The strongest fluorescence in most natural diamonds occurs at the end of the visible spectrum - the near visible violet - at about 390nm.

My scientist friends have other ramblings - would you like some more?

 

[Garry H (Cut Nut)]

T

I was luck enough a decade ago to be shown around the back room by Jeff Post at the Smithsonian gem collection. At the time the Aurora Collection was being cleaned for a fresh exhibition in London (that never happened).
I was allowed to take several photos from inches away with my then point and click camera (lost with a stolen lap top).

 

[Sithathoriunet]

You are having fun!
FYI - long wave and short wave UV used by gemologists and mineralogists are based on the fact that the only wavelengths we were capable of generating in 'black light' were based on mercury fluorescent tubes and certain filters.
TWO PROBLEMS:
1. the frequencies are all over the place - there is a GIA 2013 study in G&G that explains the issues.
2. The strongest fluorescence in most natural diamonds occurs at the end of the visible spectrum - the near visible violet - at about 390nm.

My scientist friends have other ramblings - would you like some more?

Oh Yes! Please! Thank you for all of the insight! I wonder if they might have any information on fancy white diamonds in this type of exposure...
I feel so excited! Like a little girl! Lol..

 

[Sithathoriunet]

I was luck enough a decade ago to be shown around the back room by Jeff Post at the Smithsonian gem collection. At the time the Aurora Collection was being cleaned for a fresh exhibition in London (that never happened).
I was allowed to take several photos from inches away with my then point and click camera (lost with a stolen lap top).

Oh WOW!!!! It must have been fascinating! I have never seen it in person, but one day I would love to...I have it on my gem bucket list!
Does that mean your pictures were lost with the stolen lap top and camera? Or did you have a chance before, to get them developed?

 

[Sithathoriunet]

Ok, so I stumbled across this on Gemology on line, it is an article about Fluorescence and Color Diamonds, and to date, it is the only place I have seen any image of a fancy white with reference to this effect! So, I thought I would add it for the sake of sharing.. It is very cool because there is a picture that shows the use of fluorescence and it's ability to help distinguish between natural and synthetic diamonds..
The article is said to have been from "Langerman".
Fluorescence and Color Diamonds

Often times, fluorescence is misunderstood as a negative attribute that compromises the quality of a diamond, but in most of the cases, that is far from the truth. Here are some questions and answers to clarify some murky issues concerning misconceived characteristics of fluorescence.

What is fluorescence in diamonds?
Fluorescence in diamonds refers to a tendency to emit a soft colored glow when subjected to short or long waves of ultraviolet radiation, such as a “black light” (think of how your diamond responds under a bright sun, tanning bed, or at a dance club). And even when the light source is removed, the diamond will continue to fluoresce, but only for few nanoseconds, giving off the illusion that the “glow” has stopped instantly when the light source was removed, unlike phosphorescence, which persists as an afterglow.

Fluorescence in diamond is considered as an identifying characteristic, meaning, additional information that helps to distinguish one diamond from another. Thus, it has little or no effect on a diamond’s sparkle unlike the cut and clarity criteria. Therefore, it can not weaken the diamond’s structure in any way.

Fluorescence in color diamonds.

The phenomenon of fluorescence is caused by different variations in the atomic structure, and only 30% of colorless diamonds fluoresce, while 60% to 100% of natural color diamonds emits the glow - depending on color and the origin of the stone. For example, 90% or more of blue diamonds are noted as having no observable fluorescence, but pinks diamond tend to fluoresce more than other diamonds.

Contrary to fluorescence in colourless diamonds - which is mostly blue - fluorescence in natural color diamonds varies greatly. Blue is the most common fluorescence, but there are white, orange, orange-yellow, yellow, green, and red as well.

The Aurora Butterfly of Peace. Daylight and under UV light. Photo: R. Weldon. Copyright:GIA.

How is fluorescence graded?

Fluorescence in diamond is considered as an identifying characteristic, not a grading factor like clarity and cut. Therefore, Diamond Grading Reports describe a diamond’s fluorescence by five levels of intensity - None, Faint, Medium, Strong and Very Strong.

Which diamonds fluoresce?

All types of diamonds - natural, synthetic, treated - and also stimulants can emit fluorescence, and the nature of each glow contains vital information for the gemologists to determine whether or not the diamond is synthetic or treated, depending on its response to short and long waves of ultraviolet light. GIA also uses a fluorescence imaging instrument to reveal characteristic growth patterns within crystals.

Telltale growth patterns for natural and synthetic diamonds. Photo GIA.

What are the myths around fluorescence?

Fluorescence is generally perceived as an undesirable trait. And such misconception is far from the truth, as scientific studies and professionals in the field agree that fluorescence is actually a positive characteristic most of the time. And according to HRD Antwerp “even strong fluorescence does not negatively impact a diamond’s appearance.”

Fluorescence is not a negative trait which compromises the value of the natural diamonds, therefore, it shouldn’t be a factor to bring down the price. As HRD Antwerp points out, “There are no grounds on which to justify the price penalties that currently apply to fluorescent diamonds,” which Alan Bronstein, a trusted advisor of colored diamond and the President of National Colored Diamond Industry Association (NCDIA), echoes - “Argyle pinks have fluorescence and yet it has no influence on their price.”

When does fluorescence have negative effects?

Two factors need to be taken into account: the color and the strength of the fluorescence. In exceptionally rare cases, the combination of intrinsic color of the diamond and the color and the strength of the fluorescence could possibly create a negative effect.

In a rare case of extremely high level of fluorences, it could affect the clarity and brilliance of the diamond, and the stones could appear milky or hazy to the naked eyes, making it nearly impossible to miss such symptoms.

As for the unusual case of yellow diamonds with a extremely strong blue fluorescence, the color could appear less “vivid” due to the phenomenon created by the two complementary colors - blue and yellow.

Aside from those atypical cases, GIA Fluorescence Study states that average person could not tell the difference between a diamond with or without fluorescence. And for the overwhelming majority of diamonds, the strength of fluorescence does not have noticeable effect on appearance at all.

Can fluorescence enhance the beauty your diamond?

The answer is, Yes!

While fluorescence has no negative impact on the structure and the quality of a diamond, it can enhance the beauty of a diamond.

In the case of yellow diamonds with yellow fluorescence, the color of the stones will appear even more intense, especially when viewed under strong natural light. This is also true for greenish-yellow color diamonds from Venezuela, as the fluorescence cast unique and fascinating color on them. Orange diamond with orange fluorescence will also appear much more intense and vivid in color

With or without?

Simply put, fluorescence in diamonds should not be considered as a negative trait that devalues the stones.

On the contrary to the general misunderstanding, fluorescence actually plays a positive role by contributing to the uniqueness of natural color diamonds by adding an individualized touch to each color that can not be emulated or duplicated otherwise.

At Langerman we even play with fluorescence and create extraordinary jewels with natural color diamonds that transform in various colors depending on different source of light: daylight - sunlight - ultraviolet light.

The jewels reflect personal taste. In the end it doesn’t matter if it’s with or without fluorescence. You just need to fall in love with “the one” that captures your heart.

 

[Sithathoriunet]

So, this gorgeous diamond necklace is attributed to Napoleon,

 

[Sithathoriunet]

Beautiful colored diamonds that fluoresce

 

[Sithathoriunet]

Napoleon sure had nice jewels..lol..
He presented this necklace to his second wife, Marie-Louise of Austria..lucky girl..

 

[Texas Leaguer]

Thank you Gerry! This is getting very interesting, I am wondering how many fancy white diamonds have been tested, I almost want to say that perhaps they have the ability to phosphoresce longer because of significant imperfections? Those microscopic needle like inclusions that give them the white-ness?
I wish I had the funds to purchase a few more whites just to test them...

@Sithathoriunet ,
You may very well be on to something with your speculation here. An individual diamond can have a variety of defects in the crystal lattice that are capable of interacting with one another, reinforcing or extinguishing photo luminescence.

It makes sense that a rare, homogeneous white would have many defect centers of a similar type, and you may get repeated amplification causing the phosphorescence to be significantly prolonged. A little echo chamber of luminosity

Congrats on a very cool stone, and thanks for opening a fascinating thread!

 

[Demon]

Beautiful colored diamonds that fluoresce

flur. Those are gorgeous! As is the Aurora collection. I don't have anything quite as beautiful, but I do have a couple pictures. The top picture left to right is a chameleon, the fancy green yellow with strong blue fluorescence (the one that phosphoresces but I can't get a picture of that), and my fancy intense green yellow with strong green fluorescence. The bottom picture is the fancy green yellow, the fancy intense green yellow, and a fancy yellow.

 

[Garry H (Cut Nut)]

Oh Yes! Please! Thank you for all of the insight! I wonder if they might have any information on fancy white diamonds in this type of exposure...
I feel so excited! Like a little girl! Lol..

OK - you asked for it - i will invite G to join up. He is a retired scientist.
We are lunching at Ewen Tylers invitation on Tuseday. Ewen led or was involved with the discovery of all 3 commercial diamond mines in Australia: Ellendale (Tiffany had first dibs on the yellow diamonds) Argyle, and Merlin - 105ct rock found. Ewen features in a book to be available next month about Argyle.

Interestingly Garry, with respect to minerals other than diamond, to which I'm really a totally ignorant newcomer, my own meagre experience is that visible fluorescence is strongest when excited by radiation only mildly more energetic, (ie of mildly shorter wavelength) than the emitted fluorescence. This was certainly true for excited chromic fluorescence. The "charging" for fluorescence or especially for phosphorescence seems to me to also be very sensitive to the narrow "window" of excitation wavelengths, & only a small departure from that range can be ineffective. This was noticeable for instance with yellow syn. verneuil spinel which reacts only weakly greenish-white to 405nm but intensely bright poisonous green to 385nm & 365nm.

It may in the extract attached from Burns, "Mineralogical Applications Of Crystal Field Theory", that I think I remember the comment was made that any photosensitisation & excitation significantly above ground state of a fluorescent/phosph material generally decays back to the excitation state just one level above the ground state before the fluorescence-emitting final electronic relaxation occurs, suggesting that greater excitation (eg with more energetic radiation) then doesn't necessarily directly lead to stronger or longer fluorescence (or phosphorescence). This also explains why the fluorescence spectral envelope is essentially the same for excitation across the range of effective exciting wavelengths too, the rest of the absorbed-excitation energy from relaxation from higher levels being dissipated as non-radiative processes, especially heat.

Phosphorescence is perhaps a matter of definition of course, since it is really fluorescence lasting beyond the cessation of the exciting radiation due to varying stability of the photo-excited electronic level, but for how long? (in some cases it can be microsconds, in others many hours.) As a comparison, a previous work colleague became involved in manufacture of commercially useful phosphors & was making fluoro/phosph compositions based on strontium aluminate mostly, doped with assorted REEs, especially europium, & I have a small selection of some of his mixes, most of which can be "charged" with less than about 5 minutes exposure to a simple incandescent (non-UV) bedlamp(!) upon retiring of an evening, but will still glow quite visibly blue to green to white phosphorescent next morning (in the dark tho!), ie more than quite a few hours of sustained activity. Anyway, the attached extract from Burns has some things to say about the details of electronic states leading to fluorescence & phosphorescence too, with many energy-state electronic diagrams to illustrate, & indicating that phosphorescence needs to have an electronic triplet state developed for any extended activity, qv (explained in the Burns chapter attached, see third page for a discussion about boron in diamond...). Also attached FY amusement are PDFed copies of the simpler Wikipedia descriptions of fluorescence & phosphorescence, altho not specifically about diamonds, or even gem materials for that matter, just a more general brief overview.

Also attached is a PDFed download about fluoro & phosph FYI, specifically about diamond fluorescence/phosph. & its causes etc. It suggests that SWUV excitation is generally much less effective in most instances than LW anyway. There is also another publication, a digitext, by Marfunin, on Mineral Spectroscopy, which has a good deal also to say about fluoro & phosph to various excitations, if you are interested? It's a little heavy reading in places, like Burns(!) but useful.

I think I probably earlier sent you a small selection of some of the fluorescence spectra I've been fiddling with, of my own few diamond specimens, & have recently added to it with fluorescence spectra (visible range only, because of course, fluorescence occurs across all regions of the em spectrum, XRF analysis for instance being dependent upon just such phenomena in the hard X-ray region, & many "phosphors have been commercially developed to convert otherwise wasted & useless/harmful SWUV in a Hg low pressure discharge to, for instance LWUV, such as by stuff like lead & zinc compounds, & the LWUV emission is then in turn further converted by other "phosphors" into visible range light as seen in fluorescent tube lighting.)

FYI, I have in transit at the moment, a selection of fluorescent (phospho-borate) glass specimen buttons, each deliberately doped with a different REE that causes bright fluorescence (perhaps even phosphorescence too?, not specified; samples made in Austria actually, hopefully here in a cuppla weeks???) which I hope made also more satisfy my curiosity about REE fluorescence in general & perhaps for particular relevant REE instances in especially gem materials.

Anyway, for your amusement, am attaching my very-preliminary thoughts & comments & musings so far about gem/mineral fluorescence, which I may perhaps consider later working into some sort of possible publication. Anyway, just discard this junk when you lose interest or patience, Cheers, G.

 

[Sithathoriunet]

@Sithathoriunet ,
You may very well be on to something with your speculation here. An individual diamond can have a variety of defects in the crystal lattice that are capable of interacting with one another, reinforcing or extinguishing photo luminescence.

It makes sense that a rare, homogeneous white would have many defect centers of a similar type, and you may get repeated amplification causing the phosphorescence to be significantly prolonged. A little echo chamber of luminosity

Congrats on a very cool stone, and thanks for opening a fascinating thread!

Thank you so much for the insight! "echo chamber of luminosity"- I love this terminology! The way you theorized the amplification effect makes sense and also makes me think that this ability of prolonged phosphorescence could be prevalent in these fancy white diamonds....oh oh...I may need to buy another one to test now....lol