January 24 Through February 4—TUCSON, ARIZONA: Annual show
Welcome to the GemologyOnline.com Forum
A non-profit Forum for the exchange of gemological ideas
It is currently Thu Mar 28, 2024 6:21 am

All times are UTC - 4 hours




Post new topic Reply to topic  [ 12 posts ] 
Author Message
 Post subject: vanadium emerald glow/fluorescence?
PostPosted: Mon Jan 30, 2012 10:27 pm 
Offline
Established Member
User avatar

Joined: Tue Aug 16, 2011 11:42 pm
Posts: 27
hi

i've been reading about the chromium orbital energy levels that make rubies and emeralds fluoresce, and i have a few questions..

  • does this fluorescense lead to what we see as "glow" in emeralds and rubies?
  • is iron, for instance in thai rubies, what masks the glow/fluorescence?
  • if iron is what interferes with glow, how come only burmese rubies are noted for glow, when rubies from other origins such as africa also (from what i have understood in rw hughes) do not have iron?
  • do vanadium emeralds/beryls have glow?

thanks!
-neal


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Tue Jan 31, 2012 8:33 am 
Offline
Site Admin
User avatar

Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
The "glow" you mention is more or less nonexistent in emeralds as what we see in rubies is a red, UV to blue light induced fluorescense which is masked by iron if present in enough quantity. The red fluorescense boosts the red impression of rubies, makes them "glow".
Red fluorescense from daylight in emeralds would actually dim the green impression as red and green are on the opposite side of the "colurwheel", so called complementary colours. The green colour of good emeralds is "glowing" in itself but that is not due to fluorescence but depends rather on hue and saturation level and to some extent also to lack of iron.

That rubies from Africa in general lack iron content must be a misunderstanding. Some of the rubies from Africa have very low iron content ( for instance certain stones from Mozambique) while some have pretty high iron content (typically Madagascar) which masks the fluorescense equally to rubies from other parts of the world.

Regarding "glow" in emeralds I'm sure there are several members here that can elaborate on this.

_________________
_____________
Conny Forsberg


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Tue Jan 31, 2012 10:27 pm 
Offline
Platinum Member
User avatar

Joined: Fri Feb 24, 2006 1:20 am
Posts: 2756
Location: Southern California, U.S.A.
Conny Forsberg wrote:
The "glow" you mention is more or less nonexistent in emeralds as what we see in rubies is a red, UV to blue light induced fluorescense which is masked by iron if present in enough quantity. The red fluorescense boosts the red impression of rubies, makes them "glow".
Red fluorescense from daylight in emeralds would actually dim the green impression as red and green are on the opposite side of the "colurwheel", so called complementary colours. The green colour of good emeralds is "glowing" in itself but that is not due to fluorescence but depends rather on hue and saturation level and to some extent also to lack of iron.

That's an interesting comment Conny. I've just been reading emerald dealer/author Ronald Ringsrud's book "Emeralds: A Passionate Guide," and he seems to think that low-iron Colombian emerald's green "becomes even more vibrant" due to the red daylight fluorescence. He writes that "With Colombian emeralds, the red fluorescence is not obvious, but perceived as a hidden charm."

Ringsrud attributes the special "glow" of some Colombian emeralds to the "gota de aceite" effect, caused by "growth irregularities [that] bend and soften the light." He writes that internally-reflected light "disperses through the stone more widely, thanks to these inclusions and the textures they create." He equates such internal structures with the light-dispersing inclusions in Kashmir sapphire.

_________________
Rick Martin

www.artcutgems.com


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Wed Feb 01, 2012 3:19 am 
Offline
Site Admin
User avatar

Joined: Fri Apr 17, 2009 3:53 pm
Posts: 2049
Location: Sweden
Maybe his idea is right. He has extreme experience in emeralds compared to me. I still think that visible red fluorescence would make the color weaker.

Until disproven my guess is that chromium and/or vanadium, combined with lack of iron, is affecting beryl the same way as copper sometimes does to tourmaline giving it hues and saturations that glow. I'm sure some well equipped physics labs will come with a paper on this from one of their researchers sooner or later. :)

_________________
_____________
Conny Forsberg


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Wed Feb 01, 2012 9:22 am 
Offline
Valued Contributor

Joined: Wed Oct 22, 2008 5:00 am
Posts: 344
Location: Finland
Daylight wavelengths can induce fluorescence in emerald just like in ruby, but half of it is at infrared range. Thus human eye does not see it all. I guess same thing can be said more beautifully:

Quote:
the red fluorescence is not obvious, but perceived as a hidden charm


I'm with Conny in thinking red and green is not good combination. Emerald color comes from selective absorption but fluorescence is "additional colored light source". Traditional color mixing palette doesn't work here as advertised, but combination of these two is somewhat brownish or muddy rather than "better" green.

_________________
GemmoRaman GemmoFtir GemmoSphere


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Wed Feb 01, 2012 1:57 pm 
Offline
Site Admin
User avatar

Joined: Sun Oct 16, 2005 12:22 pm
Posts: 21602
Location: San Francisco
Does anyone have some emeralds they can test and report back?


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Wed Feb 01, 2012 2:08 pm 
Offline
Platinum Member
User avatar

Joined: Fri Feb 24, 2006 1:20 am
Posts: 2756
Location: Southern California, U.S.A.
Hi Mikko,
I also felt the author was gilding the lily a bit with his "hidden charm" comment about Colombian emerald's red fluorescence. But I wanted to learn what others had to say.

For years I've been told that Colombian emerald exhibits a special "glow" not seen in emeralds from other sources. Perhaps that's entirely attributable to the low iron content allowing its true hue and saturation to be displayed, as Conny says.

I doubt the "gota de aceite/drop of oil" effect has much bearing since Ringsrud says it occurs in only one in a thousand emeralds, which must be cut with the etching and regrowth structures parallel with the table to make it visible.

I've done something similar by cutting hydrothermal synthetic emeralds with the seed crystal plate parallel with the table :lol:

_________________
Rick Martin

www.artcutgems.com


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Thu Feb 02, 2012 6:59 pm 
Offline
Gold Member
User avatar

Joined: Mon Apr 16, 2007 12:05 am
Posts: 1499
I'm pretty sure that vanadium-colored gemstones don't fluoresce red.

Chromium emerald does fluoresce red. But this fluorescence is very weak. So very weak that it is wholly undetectable under any normal, broad-spectrum lighting condition. In fact, such an emerald prefers to absorb light at the fluorescence wavelength rather than fluoresce it.


Last edited by Brian on Thu Feb 02, 2012 8:21 pm, edited 1 time in total.

Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Thu Feb 02, 2012 8:05 pm 
Offline
Gemology Online Veteran

Joined: Mon Feb 11, 2008 11:11 pm
Posts: 506
Location: Moncton, Canada
Connie and all,

I'm pretty sure there is indeed an underlying red fluourescence that accounts for the special vibrancy in the (as far as I recall virtually iron-free) Colombian emeralds; this information came from Terri Ottaway (who was then at the ROM) in the course of researching the Colombian Emeralds episode of the (Canadian) Discovery Channel precious stones series. I believe she is now at the GIA.

Cheers
Hans Durstling
Moncton Canada

_________________
Ecclesiastes 10:19


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Thu Feb 02, 2012 9:20 pm 
Offline
Gold Member
User avatar

Joined: Mon Apr 16, 2007 12:05 am
Posts: 1499
"Glow"..."vibrancy"... Whatever this magical property is, it seems quite a stretch to associate it with emerald fluorescence. I would agree with the statement that under daylight, emerald fluorescence is hidden... in fact, it digs itself a dark hole to hide in.

Let's look at ruby spectra collected with white light. See those two tall peaks at around 694 nm? Those are narrow-line fluorescence emission characteristic of chromium ions in ruby as they convert some of the green and violet light they absorb into red light.

Now let's look at emerald spectra collected with white light. See any narrow peaks in the red end of the spectrum? Cursory examination suggests that there might be a small peak in that range. But close inspection shows it is actually two divots at around 684 nm. The divots demonstrate that, under white light, the chromium ions in emerald prefer to absorb light at those particular red wavelength rather than fluoresce light.

As seen in the third graph in this thread, you can make the chromium ions in ruby absorb red, rather than fluoresce. This emerald-like behavior is described in this link. The discussion is a bit long-winded, but might shed some light on how chromium ions in ruby and emerald behave.


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Fri Feb 03, 2012 4:55 am 
Offline
Site Admin
User avatar

Joined: Fri May 12, 2006 11:24 am
Posts: 7523
Location: Rome, Italy
hey Brian,

thank you very much for resuscitating those VERY interesting Thread!! =D> =D>
there are so much interesting stuffs over here!! It's a real pity sometimes i forgot'em.... :oops:

ciao
albé

_________________
GemmoRaman-532 - GemmoFTIR - GemmoSphere - EXA


Top
 Profile  
Reply with quote  
 Post subject: Re: vanadium emerald glow/fluorescence?
PostPosted: Tue Jun 18, 2013 8:24 pm 
Offline
Established Member

Joined: Sat Jun 30, 2012 10:27 pm
Posts: 37
According to ron ringsrud interesting post http://www.emeraldmine.com in emerald there is two peaks in the spectra one in the blue zone and one in the red and our eye perceives that as green , if therefore the colombian emeralds have more red and some red flourescence could our eye pick up on the warm glow that is mentioned in rons book ?


Top
 Profile  
Reply with quote  
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 12 posts ] 

All times are UTC - 4 hours


Who is online

Users browsing this forum: No registered users and 16 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

Search for:
Jump to:  
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
Gemology Style ported to phpBB3 by Christian Bullock