Spinels and fluorescence

[klewis]

I love seeing all the red/pink spinels being shown on coloured stone forum, I''d love have one some day (soon). I''m interested in the importance of fluorescence. It gets mentioned a lot and I keep wanting to ask this every time a red/pink spinel appears on PS but haven''t because I''m trying to reform my threadjack ways.

Is fluorescence visible by normal viewing of the stone? If so, why is it necessary to use a UV light? If fluorescence has to be confirmed by UV light, why does it matter so much? Shouldn''t the colour quality be judged just by viewing the stone under normal lighting conditions? Is it perhaps that a spinel that fluoresces will show better colour than one that doesn''t and so do all the good colour spinels fluoresce?
To fluoresce or not to fluoresce, that is the question? And finally, if it is so important, couldn''t we give it a name that I don''t have to check every time I spell it?

 

[T L]

Date: 11/28/2009 4:27:31 PM
Author:klewis
I love seeing all the red/pink spinels being shown on coloured stone forum, I''d love have one some day (soon). I''m interested in the importance of fluorescence. It gets mentioned a lot and I keep wanting to ask this every time a red/pink spinel appears on PS but haven''t because I''m trying to reform my threadjack ways.

Is fluorescence visible by normal viewing of the stone? If so, why is it necessary to use a UV light? If fluorescence has to be confirmed by UV light, why does it matter so much? Shouldn''t the colour quality be judged just by viewing the stone under normal lighting conditions? Is it perhaps that a spinel that fluoresces will show better colour than one that doesn''t and so do all the good colour spinels fluoresce?
To fluoresce or not to fluoresce, that is the question? And finally, if it is so important, couldn''t we give it a name that I don''t have to check every time I spell it?

There is some UV light that gets to us by sunlight, so it is possible to see some fluorescence in sunlight. For example, many diamonds fluoresce and it is possible to see it in sunlight. When a gem of a certain color has a complimenting color fluorescence, such as red fluorescence in a pink spinel, the color is enhanced even more when one goes outside on a sunny day. This is the nice aspect of fluorescence. Of course one best sees the true fluorescence using a pure UV light in the dark.

 

[LD]

Totally agree with TL. Fluorescence whilst clearly visible with UV light (to confirm it''s presence and just to go W

W!) also will have an affect on how the gemstone performs.

I''m going to show you a diamond. This is an I colour - which in normal circumstances you''d expect would be starting to show a warm colour. You wouldn''t say a normal I colour was white like an F for example. However, combine it with strong fluorescence and the blue of the fluor cancels out the yellow of the diamond so what you get is (in most cases) a gemstone that appears to be whiter than it''s actual grade.

So here''s the diamond. The first photo is in natural light inside - with light coming through the window. You can''t see any yellow. The second photo shows it in strong sunlight - can you see the blue tinge? That''s not a reflection. That''s the fluor.

Ok - so that''s how it affects my diamond. Now look at the pictures of my spinel. With the fluor it glows and the colour is super-enhanced in sunlight. In fact, this gem very rarely does anything other than glow. I''m sure that the fluor is the reason.

The other effect of fluor is that it can actually help gemstones to appear to change colour (or that they do change colour). I have a pear sapphire that I bought recently that changes from a blue/violet to a purple. It fluoresces red.

Hope that helps.

 

[T L]

fluor isn''t always a good thing though. I have a pink champagne diamond with strong blue fluorescence. Well, when outside, this fluor kind of washes out the pink color a little bit. Some people avoid colorless diamonds with strong fluorescence, and some people look for them. However, with Mahenge spinels, fluorescence is typically red (I don''t think it fluors any other color) and this can only enhance the color, so it''s a good thing, and should be present if you''re spending a great deal on a Mahenge.

 

[klewis]

TL and LD - Thanks. Interesting diamond stories and I can see the marked effect in the diamond photos you posted LD. I can understand better now how, in relation to red/pink spinels, fluorescence enhances the colour but why isn''t fluorescence mentioned much on sites selling these stones?
TL and LD, would you have known by the performance of the stones that you''ve mentioned and posted pics of that the effects you were seeing were the result of fluorescence and is it something that cutters and dealers identify immediately when looking at rough or a cut stone.
A lot of questions, I know and apologies if this is learner stuff and completely obvious to everyone else.

 

[Indylady]

I''m enjoying this thread! Fly Girl has a thread about her rubies in which there is a shot of her Burmese ruby fluorescing red by a diamond fluorescing blue. Its a really neat picture. I think the picture was taken by the vendor, Dutton''s Diamonds.

 

[Fly Girl]

It's more that you suspect a stone has fluorescence because the color is a bit more vivid when there is UV light present. I have a Burmese ruby with strong red fluorescence, and I have sometimes glanced down when I'm out in the sun, and caught it absolutely glowing. It takes your breath away. I strongly suspected my Mahenge spinel had fluor, just because the color was so vivid. As to why it isn't mentioned by vendors, well, there is the education of the consumer aspect that has to take place before it means much.

ETA-I was typing at the same time as szh07. Thank you. The thread you are referring to is here. Link

 

[T L]

The Hope diamond is also famed not only because it's huge and blue, but it's a very rare form of blue diamond that fluoresces red!!

Here is the Hope in UV light below, and notice one of the side diamonds has some blue fluor.

As with top Mahenge spinels, I wouldn't buy an expensive Burmese ruby that didn't fluoresce red as well. It really gives an incredible punch of color in the sun.

 

[T L]

Date: 11/28/2009 6:40:00 PM
Author: klewis
TL and LD - Thanks. Interesting diamond stories and I can see the marked effect in the diamond photos you posted LD. I can understand better now how, in relation to red/pink spinels, fluorescence enhances the colour but why isn't fluorescence mentioned much on sites selling these stones?
TL and LD, would you have known by the performance of the stones that you've mentioned and posted pics of that the effects you were seeing were the result of fluorescence and is it something that cutters and dealers identify immediately when looking at rough or a cut stone.
A lot of questions, I know and apologies if this is learner stuff and completely obvious to everyone else.

Klewis,
Well, I think like others have said, it is important to educate yourself about fluor and to have a UV light if you are a gem collector. As for fluor giving vivid color, it's not a necessity. For example, I have very vivid stones that do not have any fluorescence, in fact some stones just do not by the nature of their chemical makeup, but can be vivid in color (paraiba tourmaline is an example). However, for stones that typically have fluor like Burmese rubies, Mahenge spinels, and some colored and colorless diamonds, it is important to evaluate the stone with fluor, and a must have in some of those stones (rubies and red spinels).

 

[klewis]

Date: 11/28/2009 6:45:20 PM
Author: szh07
I''m enjoying this thread! Fly Girl has a thread about her rubies in which there is a shot of her Burmese ruby fluorescing red by a diamond fluorescing blue. Its a really neat picture. I think the picture was taken by the vendor, Dutton''s Diamonds.

I saw that photo too. A really interesting pic.

 

[klewis]

Date: 11/28/2009 6:51:57 PM
Author: tourmaline_lover
The Hope diamond is also famed not only because it''s huge and blue, but it''s a very rare form of blue diamond that fluoresces red!!

Here is the Hope in UV light below, and notice one of the side diamonds has some blue fluor.


As with top Mahenge spinels, I wouldn''t buy an expensive Burmese ruby that didn''t fluoresce red as well. It really gives an incredible punch of color in the sun.

Wow great pic, thanks TL. I can see how red fluor would add some punch to a pink stone, but how does red fluor enhance a blue stone? Should I be sent the colour basics school?

 

[T L]

Date: 11/28/2009 7:09:38 PM
Author: klewis

Date: 11/28/2009 6:51:57 PM
Author: tourmaline_lover
The Hope diamond is also famed not only because it's huge and blue, but it's a very rare form of blue diamond that fluoresces red!!

Here is the Hope in UV light below, and notice one of the side diamonds has some blue fluor.


As with top Mahenge spinels, I wouldn't buy an expensive Burmese ruby that didn't fluoresce red as well. It really gives an incredible punch of color in the sun.

Wow great pic, thanks TL. I can see how red fluor would add some punch to a pink stone, but how does red fluor enhance a blue stone? Should I be sent the colour basics school?

Actually, I was mistaken (my apologies), the Hope produces a red phosphorescence (something else to confuse you!!).

http://www.sciencedaily.com/releases/2008/01/080104145404.htm

One of the strangest stones to fluor red is alexandrite. It typically is green outdoors though, so evidently, the red fluorescence has no effect on it. I have an alexandrite that has strong red fluor in UV light, but this does not show up at all when I take it outside, in fact it goes a teal color outdoors. I do not know why.

 

[klewis]

Date: 11/28/2009 7:15:55 PM
Author: tourmaline_lover

Date: 11/28/2009 7:09:38 PM

Author: klewis

Date: 11/28/2009 6:51:57 PM

Author: tourmaline_lover

The Hope diamond is also famed not only because it''s huge and blue, but it''s a very rare form of blue diamond that fluoresces red!!

Here is the Hope in UV light below, and notice one of the side diamonds has some blue fluor.



As with top Mahenge spinels, I wouldn''t buy an expensive Burmese ruby that didn''t fluoresce red as well. It really gives an incredible punch of color in the sun.

Wow great pic, thanks TL. I can see how red fluor would add some punch to a pink stone, but how does red fluor enhance a blue stone? Should I be sent the colour basics school?

Actually, I was mistaken (my apologies), the Hope produces a red phosphorescence (something else to confuse you!!).


http://www.sciencedaily.com/releases/2008/01/080104145404.htm


One of the strangest stones to fluor red is alexandrite. It typically is green outdoors though, so evidentally, the red fluorescence has no effect on it. I have an alexandrite that has strong red fluor in UV light, but this does not show up at all when I take it outside, in fact it goes a teal color outdoors. I do not know why.

Hey, you''re supposed to be making this easier. You knew I was having trouble with fluorescence and now you introduce phosphorescence?

 

[LD]

KLewis - once you''ve seen a few stones that have fluor, you kind of suspect it with some gemstones. For example, the sapphire I recently bought had "something" about it. I was sure that the effect I was seeing was magnified by fluor and sure enough it was!

Again TL is correct. My Alexandrites fluoresce red BUT they appear green during the day and purple/pink/red at night! I have a photo somewhere so will try and find it.

As to why it''s not disclosed? In certified diamonds it normally is and for many years it''s been considered a bad thing for a diamond to have. Years ago, diamonds "blue white" with fluor were very sought after. Not sure why the market made a shift in the other direction but it did and thankfully it''s moving back as people are rediscovering and loving it!

In terms of coloured gemstones, I can''t tell you how many vendors (big names) I''ve asked if a stone has fluor and been told that they don''t have the capability to test!!!! I''ve also been warned off using a UV light to test fluor as it can be dangerous. I suspect there are different types of UV light but the little torches I use are from Ebay and cheap!

 

[T L]

Date: 11/28/2009 7:37:56 PM
Author: LovingDiamonds
KLewis - once you've seen a few stones that have fluor, you kind of suspect it with some gemstones. For example, the sapphire I recently bought had 'something' about it. I was sure that the effect I was seeing was magnified by fluor and sure enough it was!

Again TL is correct. My Alexandrites fluoresce red BUT they appear green during the day and purple/pink/red at night! I have a photo somewhere so will try and find it.

As to why it's not disclosed? In certified diamonds it normally is and for many years it's been considered a bad thing for a diamond to have. Years ago, diamonds 'blue white' with fluor were very sought after. Not sure why the market made a shift in the other direction but it did and thankfully it's moving back as people are rediscovering and loving it!

In terms of coloured gemstones, I can't tell you how many vendors (big names) I've asked if a stone has fluor and been told that they don't have the capability to test!!!! I've also been warned off using a UV light to test fluor as it can be dangerous. I suspect there are different types of UV light but the little torches I use are from Ebay and cheap!

It's one of the easiest things to test. The danger comment is ridiculous as well!! I'm sorry. We're not checking for gamma rays here!!

 

[LD]

Date: 11/28/2009 7:46:20 PM
Author: tourmaline_lover

Date: 11/28/2009 7:37:56 PM
Author: LovingDiamonds
KLewis - once you''ve seen a few stones that have fluor, you kind of suspect it with some gemstones. For example, the sapphire I recently bought had ''something'' about it. I was sure that the effect I was seeing was magnified by fluor and sure enough it was!

Again TL is correct. My Alexandrites fluoresce red BUT they appear green during the day and purple/pink/red at night! I have a photo somewhere so will try and find it.

As to why it''s not disclosed? In certified diamonds it normally is and for many years it''s been considered a bad thing for a diamond to have. Years ago, diamonds ''blue white'' with fluor were very sought after. Not sure why the market made a shift in the other direction but it did and thankfully it''s moving back as people are rediscovering and loving it!

In terms of coloured gemstones, I can''t tell you how many vendors (big names) I''ve asked if a stone has fluor and been told that they don''t have the capability to test!!!! I''ve also been warned off using a UV light to test fluor as it can be dangerous. I suspect there are different types of UV light but the little torches I use are from Ebay and cheap!

It''s one of the easiest things to test. The danger comment is ridiculous as well!! I''m sorry. We''re not checking for gamma rays here!!

I agree! I''m not going to say who it was because he posts on here but I just thought "oh well" and ignored the health warning!

 

[colormyworld]

Date: 11/28/2009 7:46:20 PM
Author: tourmaline_lover

Date: 11/28/2009 7:37:56 PM
Author: LovingDiamonds
KLewis - once you've seen a few stones that have fluor, you kind of suspect it with some gemstones. For example, the sapphire I recently bought had 'something' about it. I was sure that the effect I was seeing was magnified by fluor and sure enough it was!

Again TL is correct. My Alexandrites fluoresce red BUT they appear green during the day and purple/pink/red at night! I have a photo somewhere so will try and find it.

As to why it's not disclosed? In certified diamonds it normally is and for many years it's been considered a bad thing for a diamond to have. Years ago, diamonds 'blue white' with fluor were very sought after. Not sure why the market made a shift in the other direction but it did and thankfully it's moving back as people are rediscovering and loving it!

In terms of coloured gemstones, I can't tell you how many vendors (big names) I've asked if a stone has fluor and been told that they don't have the capability to test!!!! I've also been warned off using a UV light to test fluor as it can be dangerous. I suspect there are different types of UV light but the little torches I use are from Ebay and cheap!

It's one of the easiest things to test. The danger comment is ridiculous as well!! I'm sorry. We're not checking for gamma rays here!!

Short wave UV light will harm you. Posts like the above can be dangerous to others who read and believe what you say.

 

[LD]

Date: 11/28/2009 7:58:10 PM
Author: colormyworld

Date: 11/28/2009 7:46:20 PM
Author: tourmaline_lover

Date: 11/28/2009 7:37:56 PM
Author: LovingDiamonds
KLewis - once you''ve seen a few stones that have fluor, you kind of suspect it with some gemstones. For example, the sapphire I recently bought had ''something'' about it. I was sure that the effect I was seeing was magnified by fluor and sure enough it was!

Again TL is correct. My Alexandrites fluoresce red BUT they appear green during the day and purple/pink/red at night! I have a photo somewhere so will try and find it.

As to why it''s not disclosed? In certified diamonds it normally is and for many years it''s been considered a bad thing for a diamond to have. Years ago, diamonds ''blue white'' with fluor were very sought after. Not sure why the market made a shift in the other direction but it did and thankfully it''s moving back as people are rediscovering and loving it!

In terms of coloured gemstones, I can''t tell you how many vendors (big names) I''ve asked if a stone has fluor and been told that they don''t have the capability to test!!!! I''ve also been warned off using a UV light to test fluor as it can be dangerous. I suspect there are different types of UV light but the little torches I use are from Ebay and cheap!

It''s one of the easiest things to test. The danger comment is ridiculous as well!! I''m sorry. We''re not checking for gamma rays here!!

Short wave UV light will harm you. Posts like the above can be dangerous to others who read and believe what you say.

Most of us use these (or a version of these) to test fluor. Surely these aren''t dangerous?????????????????

http://cgi.ebay.co.uk/5-LED-Mini-UV-Blacklight-KeyChain-Torch-Flashlight-m_W0QQitemZ380180093334QQcmdZViewItemQQptZUK_SportsLeisure_Camping_LightsLanternsTorches?hash=item58847fd996

 

[cushioncutnut]

Date: 11/28/2009 8:03:08 PM
Author: LovingDiamonds

Date: 11/28/2009 7:58:10 PM
Author: colormyworld

Date: 11/28/2009 7:46:20 PM
Author: tourmaline_lover

Date: 11/28/2009 7:37:56 PM
Author: LovingDiamonds
KLewis - once you''ve seen a few stones that have fluor, you kind of suspect it with some gemstones. For example, the sapphire I recently bought had ''something'' about it. I was sure that the effect I was seeing was magnified by fluor and sure enough it was!

Again TL is correct. My Alexandrites fluoresce red BUT they appear green during the day and purple/pink/red at night! I have a photo somewhere so will try and find it.

As to why it''s not disclosed? In certified diamonds it normally is and for many years it''s been considered a bad thing for a diamond to have. Years ago, diamonds ''blue white'' with fluor were very sought after. Not sure why the market made a shift in the other direction but it did and thankfully it''s moving back as people are rediscovering and loving it!

In terms of coloured gemstones, I can''t tell you how many vendors (big names) I''ve asked if a stone has fluor and been told that they don''t have the capability to test!!!! I''ve also been warned off using a UV light to test fluor as it can be dangerous. I suspect there are different types of UV light but the little torches I use are from Ebay and cheap!

It''s one of the easiest things to test. The danger comment is ridiculous as well!! I''m sorry. We''re not checking for gamma rays here!!

Short wave UV light will harm you. Posts like the above can be dangerous to others who read and believe what you say.

Most of us use these (or a version of these) to test fluor. Surely these aren''t dangerous?????????????????

http://cgi.ebay.co.uk/5-LED-Mini-UV-Blacklight-KeyChain-Torch-Flashlight-m_W0QQitemZ380180093334QQcmdZViewItemQQptZUK_SportsLeisure_Camping_LightsLanternsTorches?hash=item58847fd996

No kidding???

I will keep that in mind not that I use my little UV flashlight that often....

 

[T L]

Apparently looking directly at pure UV light will hurt your eyes, and it can harm your skin. Here's an article on the different kinds of UV lighting used.

http://www.minershop.com/html/what_is_uv_.html

 

[LD]

Date: 11/28/2009 8:09:28 PM
Author: tourmaline_lover
Apparently looking directly at pure UV light will hurt your eyes. Here''s an article on the different kinds of UV lighting used.

http://www.minershop.com/html/what_is_uv_.html

Better stop going to discos then! lol

 

[T L]

. . . or tanning salons. UV light damage on your skin is also called tanning. The cheapie little UV led lights I get on ebay seem very harmless. I have never hurt my eyes or skin from them. Gemologists do use shortwave lights to test gems fluorescence though, and they emit the more dangerous form of UV light, but again, going out in the sun can be harmful too. I guess with anything like this, some caution should be exercised.

 

[colormyworld]

Date: 11/28/2009 8:12:31 PM
Author: LovingDiamonds

Date: 11/28/2009 8:09:28 PM
Author: tourmaline_lover
Apparently looking directly at pure UV light will hurt your eyes. Here''s an article on the different kinds of UV lighting used.

http://www.minershop.com/html/what_is_uv_.html

Better stop going to discos then! lol

LD I am pretty sure that would be lLWUV not SWUV

 

[Indylady]

Hehe LD, that reminds me of a pic of Disco Stu from the Simpsons

 

[empress]

klewis - one caveat on red/pink spinels

The flux-grown red and pink spinels are almost impossible to tell from high quality natural red and pink spinel without lab equipment. They do show and orange-red fluorescence and the same RI, SG and spectroscope readings. Their inclusions are different examined through a microscope - but not always detectible. Raman analysis can distinguish the difference as can chemical analysis.

 

[klewis]

OK, so now I know I''m going to have to hang up my white John Travolta "stayin'' alive" suit and forgo discos forever more
I can see though I need to see some stones that do fluoresce. Who knows maybe I have one that does. Thanks too for the caution about UV light., that''s actually an important consideration.

 

[chrono]

I second/third the caution around short wave UV testing. As for the rest of the pros and cons, TL and LD both covered all the bases.

 

[kas baby]

Interesting thread about fluorescence.

I remember having some chem/bio/and genetics labs where we had to use a certain type of UV light in the experiment. We had to wear gloves and special tinted goggles. We also had to write up extra stuff in the safety procedures for the lab reports.

 

[klewis]

And to add to the mix, I was looking at references to fluorescence in the book Secrets of the Gem Trade and in the discussion on Pink Spinel there ia a mention of "transmission luminescence", a kind of purple secondary hue. Is this a different phenomenon to Fluorescence and does anyone have a spinel that shows this?

 

[Largosmom]

No one has said if there is a safe way to use a UV light to test stones--or if there is another way to test fluorescence.

Laura