Strange Stone - Vanadium Chrysoberyl

[LD]

Ok gem buffs, I need your brains on this one please!

I bought a 1.35ct Vanadium Chrysoberyl from AJS. It''s a glorious minty green colour in the day and looks exactly like the Vendors picture (see below).

This is where it gets strange ...............

At night the mintyness completely disappears and in incandescent light I see silver/grey/pink - no green at all. It''s almost like a weak colour change of an Alexandrite. Of course, being from the same family there is every possibility that it has a predisposition to change colour but this is just odd!

It also has VERY strong fuscia pink fluorescence.

So, my questions, as I can''t seem to find answers anywhere:-

1. Do all members of the Chrysoberyl family have a tendancy to colour change?
2. Should a Vanadium Chrysoberyl change colour?

I apologise for the lousy photographs but, as with Alexandrite, I cannot capture the daylight minty green at all.

 

[LD]

This is the incandescent colour (perhaps slightly less pink than the photograph shows).

 

[LD]

Here''s the fluorescence - very strong for such a pale stone.

Thanks for looking and any help would be appreciated!

 

[Kismet]

Wow, what a neat color change. My vanadium chrysoberyl does not change color at all. It''s minty green in all lights. I don''t think I''ve checked its fluorescence. My yellow chrysoberyls look somewhat greener in various lighting conditions. My green chrysoberyl looks (dark) true green under fluorescent light but olive green under sunlight/incandescent light.

 

[LD]

Oh thank you Kismet. Can you post photos? Is the green similar to the minty green I''ve posted above???????

Can you actually photograph it and capture the colour? I''m wondering if the reason I can''t is because it colour changes (i.e. same problem I have with all my colour change stones).

 

[Kismet]

This is my vanadium chrysoberyl. The picture is mostly accurate; the color is pretty spot on just not as saturated as the picture implies.

 

[LD]

Brilliant photo and lovely stone Kismet. Thank you for sharing.

Well the first difference is obvious - you can photograph it and capture the green! The second difference is that yours is far more green than mine. I''d love to know if yours has fluor or not. Would it be too much trouble to ask you to look for me please? I wonder if that''s the difference between the two????

 

[VapidLapid]

Very interesting. And the stone is lovely. I have been eyeing those at AJS for a few months and your posting this morning pushed me off my chair. I bought one even before walking the dog!

You all have likely discerned that science is like a hobby to me. I think of it more as a lifestyle but I know some folks who think my life is all hobby. Not a bad hobby to have!
One of my Go To sources for propertied of things is Theodore Gray''s Wooden Periodic Table. My desidre for the cobalt spinel was partly to represent Cobalt in my own collection of elements. Here is the link to the page about Vanadium.

http://theodoregray.com/PeriodicTable/Elements/023/index.s7.html

from there you can get all over his site. Dont miss the video where he makes ice cream in 10 seconds with liquid nitrogen!

 

[Kismet]

Date: 4/5/2010 12:24:39 PM
Author: LovingDiamonds
Brilliant photo and lovely stone Kismet. Thank you for sharing.


Well the first difference is obvious - you can photograph it and capture the green! The second difference is that yours is far more green than mine. I''d love to know if yours has fluor or not. Would it be too much trouble to ask you to look for me please? I wonder if that''s the difference between the two????

Sure I can check for you when I get home. If it does fluoresce, no guarantees on a picture. I haven''t been able to take a decent picture under black light yet; mine all come out purple or way over exposed or both.

 

[Barrett]

cool stone..look at that sucker glow..

 

[Barrett]

I still am in the camp that all stones color shift under two totally different lights..some color change..alex or your stone but i think all shift to some extent..it''s inevitable

 

[gingersnap]

Sorry, not helping here, but wow! That''s such a neat stone

I love that minty color. What are you going to do with it?

 

[ma re]

Don''t have the answers, but it''s a lovely stone even with a color change (if not even more because of it)!

 

[platinumrock]

I''m no help, but that is such a COOL stone, LD! I love the color shift between minty green and pink.

And that fluoro is just

 

[zeolite]

https://www.pricescope.com/community/threads/purple-and-color-change.110250/

Incidentally the following explanation is not just my words. It was given to me directly, verbally, by Dr. James Shigley, then of GIA research (now in another GIA position). He was doing detailed chemical analysis of my CC spinel and CC sapphire at that time.

The physics of all other color change gems is this: All color change stones have a broad absorption band somewhere in the yellow region, which normal gems do not have. This band is caused by as vanadium and/or other trace metals. The position of the band (green, yellow-green, yellow, orange) determines the two different colors that are shown (red - green, red - blue, peridot green - orange, etc).

The absorption band blocks mid-wavelength colors (yellow-green, yellow, and orange). If you view a color change gem in daylight, there is little red, yellow is blocked, so the gem shows cool colors (green or blue). If you view that same gem in incandescent light, there is little blue, and yellow is blocked, so the gem shows warm colors (orange or red).

The cause of the color change is the width and position of the mid-wavelength absorption band.

LD: Do all members of the Chrysoberyl family have a tendancy to colour change? There is nothing inherent about chrysoberyl and color change. Keep in mind that garnets, spinels, sapphires, and diaspore also color change. What causes the color change, is the yellow region absorption band.
Should a Vanadium Chrysoberyl change colour? Maybe, depending on the strength of the absorption band. Keep in mind that vanadium is the main coloring agent in tsavorite, and one of the two coloring agents in chrome tourmaline, yet neither of them change color.
The strength of the yellow absorption region is affected by the relative concentrations of chromium, vandium, and iron.

Amguy: I still am in the camp that all stones color shift under two totally different lights

All gems change color slightly in different lighting. Only when the change is strong, do we call them color change.

 

[LD]

Date: 4/5/2010 2:47:37 PM
Author: zeolite

https://www.pricescope.com/community/threads/purple-and-color-change.110250/

Incidentally the following explanation is not just my words. It was given to me directly, verbally, by Dr. James Shigley, then of GIA research (now in another GIA position). He was doing detailed chemical analysis of my CC spinel and CC sapphire at that time.

The physics of all other color change gems is this: All color change stones have a broad absorption band somewhere in the yellow region, which normal gems do not have. This band is caused by as vanadium and/or other trace metals. The position of the band (green, yellow-green, yellow, orange) determines the two different colors that are shown (red - green, red - blue, peridot green - orange, etc).

The absorption band blocks mid-wavelength colors (yellow-green, yellow, and orange). If you view a color change gem in daylight, there is little red, yellow is blocked, so the gem shows cool colors (green or blue). If you view that same gem in incandescent light, there is little blue, and yellow is blocked, so the gem shows warm colors (orange or red).

The cause of the color change is the width and position of the mid-wavelength absorption band.

LD: Do all members of the Chrysoberyl family have a tendancy to colour change? There is nothing inherent about chrysoberyl and color change. Keep in mind that garnets, spinels, sapphires, and diaspore also color change. What causes the color change, is the yellow region absorption band.

Should a Vanadium Chrysoberyl change colour? Maybe, depending on the strength of the absorption band. Keep in mind that vanadium is the main coloring agent in tsavorite, and one of the two coloring agents in chrome tourmaline, yet neither of them change color.
The strength of the yellow absorption region is affected by the relative concentrations of chromium, vandium, and iron.

Amguy: I still am in the camp that all stones color shift under two totally different lights

All gems change color slightly in different lighting. Only when the change is strong, do we call them color change.

Thank you Zeolite - very interesting. I actually collect colour change gemstones (some of which you''ve mentioned) and am fascinated by colour shifts and colour changes. I don''t know why I was surprised that this stone changed colour! I just wasn''t expecting it to! So building from your information above, Vanadium will play a part in the changing colour but it needs to be combined with other trace elements as well as Vanadium alone won''t guarantee a shift/change? If so, I suspect that this will have a chromium content.

In terms of the pink highlighted section, my understanding is that a "colour shift" is when a gem changes to a colour next to it on the colour wheel. However, only those gems that "change colour" to the opposite side of the colour wheel are deemed colour changes. I don''t believe the strength of colour denotes whether they''re a shifter or a changer.

 

[Barrett]

glad to hear it from you Mr. Zeo..someone with good experience like yourself..the thing is I always hear and see folks wnating or saying things like.."i want a color shift this..or a color shift that..or check out the color shift on this sapphire or what have you...well..all stones will color shift due to lighting..so really buying something because it''s a color shifter is really pointless...now some will not shift but change(jump the wheel) or some will shift much stronger..those are the ones that make sense to buy if you are looking for that..just like my tanzy crystals..heck..the shift under incad and flour. is striking and huge..but..don''t see folks selling tanzy''s as shifters..they are just tanzys''..they shift 5 times as much as stones people buy for the "color shift"
you have seen these pics before..all my crystals do this..some more so than other but all do it..looks like 2 totally different stones..color is a funtion of light..some like LD''s sweet chryso have a much stronger shift/change than many other stones and are very cool to have..didn''t even expect it did you LD..LOL

 

[Barrett]

hmm...is this a different stone? look at that shift..it''s almost a complete color change..with a tanzy..say what??

 

[Barrett]

would be nice to get a chem. readout on a stone like that LD..could be lots of goodies inside..i know nothing about them so can't comment very much..the info zeo provided is great..I also agree LD that the strength of color shouldn't play a role in amount of shift/change

 

[zeolite]

LD: I think we are saying the same thing, but are getting tangled up in words

my understanding is that a "colour shift" is when a gem changes to a colour next to it on the colour wheel. Yes

However, only those gems that "change colour" to the opposite side of the colour wheel are deemed colour changes. Yes

I don''t believe the strength of colour denotes whether they''re a shifter or a changer. No, using amguy''s superb example: I’m not saying going from pale pink to purple is a shift and intense pink to purple is a change. I’m saying going from pink to purple is the opposite side of the color wheel, and is a color change.

hmm...is this a different stone? look at that shift..it''s almost a complete color change.. amguy, do you still have that crystal? I’d like to see what (at that other gem website) Bruce’s spectroscope would say about this crystal. I have a spectroscope, but it is not a high quality, expensive one.

 

[Barrett]

sad to say that was the first tanzy crystal i ever sold..been gone over a year..sold my last 101.05ct blue a few days ago..have three that should be back from heating this week but they were odd colored ones..started out unheated as green and pale yellow..not sure what those will do..I did have a little report..did i post it on here..maybe? used multiple tanzy crystals under incad, flour, sunlight, 4700K, and tungsten to show different shifts per different lighting..where did i post that..was it here or the other site..might have been robert james site

 

[Barrett]

I have an 80ct one coming hopefully in a few weeks.that it close to identical in color as this one was..won't know about shift until i get it in hand but blue is very close..if similar will have bruce check it..have some cuprians I need looked at so it's easy for me to send that 80ct one along if it's similar to this one..may not be but all come from same guy..actually had Robert james run some test on one bi-color..never got final report..he used it as an example in Tucson this year..he was surprised by amount of shift in color also when i showed these photos and others..standard incad like you buy at wal-mart and ott light

 

[LD]

Very interesting gentlemen. Thank you.

I love your piccies of the Tanzy crystal Amguy. Now, I know this probably isn''t going to make any sense to anybody apart from me (because I''m thinking aloud!) but Tanzy has trichroism so is this what we''re seeing? So it''s not a shifter/changer per se - i.e. it doesn''t hold one colour in, say, incandescent lighting? Amguy imagine if you rotated that gem in incandescent lighting and it had been faceted do you think you''d probably get blue/purple/pink and maybe some red showing rather than a solid block of one colour (not sure if crystals react the same?)?

 

[Barrett]

yea trichoric is correct but as you can see in the photo..gem is same angle..same side same everything..don't see the flour in pic but it's slightly above and behind like the incad is..so what we are seeing is not a function of pleochorism..i can't comment LD on a cut stone as you know i am no expert or even close on cut stones..let me add one more thing..you guys have seen my green and blue bi-color crystal..thats the one I sent to ISG for testting and the subsequent report used at Tuscon..Robert said it was and is the only quad(not right term) but 4 color stone(pleochoric) he has ever seen or heard of..with the green and blue both showing dichorism..2 colors dichorism on both = 4 colors...no other gem or mineral type in the world shows this function

 

[Barrett]

here is the direct quote
What I am finding most interesting about the specimens I have received (one was mine)they are not bi-color.....that are quad-color. Purple, blue, yellow, green. Which negates that idea of calling it tanzanite as that would not fully define what we have. These are potentially quite remarkable stones on both a gemological and marketing level.

Once we can establish exactly the gemological condition of the material, I see the marketing potential of this material as quite remarkable.

I will try to get some images posted up before I leave for Tucson. I believe that this will be the first time in my 39 years at this that I have seen a gemstone offer 4 colors in the same image

 

[LD]

Date: 4/5/2010 4:11:59 PM
Author: amethystguy
here is the direct quote
What I am finding most interesting about the specimens I have received (one was mine)they are not bi-color.....that are quad-color. Purple, blue, yellow, green. Which negates that idea of calling it tanzanite as that would not fully define what we have. These are potentially quite remarkable stones on both a gemological and marketing level.

Once we can establish exactly the gemological condition of the material, I see the marketing potential of this material as quite remarkable.

I will try to get some images posted up before I leave for Tucson. I believe that this will be the first time in my 39 years at this that I have seen a gemstone offer 4 colors in the same image

Now THAT''S a good story! WOW! What are your plans with it?

Presumably it''s an unheated "Tanzanite"? I''ve certainly seen ones where they have distinct blue/green, blue/yellow but never a four way split. All of the bi-colours I''ve seen have been unheated but the blue/purple haven''t been as vivid as their heated counterparts - nonetheless, very beautiful and interesting gemstones.

 

[T L]

Cool stone LD. Could it be that alexandrite contains vanadium as well, and hence this is both a vanadium chrysoberyl and an alexandrite???

David Weinberg is an alexandrite expert, so perhaps you could ask him as well since you are a good customer of his. I bet he would be interested in seeing this stone.

 

[stepcutgirl]

I have nothing to add. Just wanted to tell you I really like it!

 

[LD]

Date: 4/5/2010 4:20:50 PM
Author: tourmaline_lover
Cool stone LD. Could it be that alexandrite contains vanadium as well, and hence this is both a vanadium chrysoberyl and an alexandrite???

David Weinberg is an alexandrite expert, so perhaps you could ask him as well since you are a good customer of his. I bet he would be interested in seeing this stone.

Funny you should say that but I''ve been debating asking David - I just felt a bit cheeky because I didn''t get it from him.

I have asked AJS and they''re perpexled. Arnold is away on business so Rung is going to try and contact him.

I guess my main issue is (a) I do love the stone but (b) want to know if this is the strangest Alex in the world OR whether it''s a Vanadium Chrysoberyl. I guess either way I''ve paid a fair price but I just hate not knowing!

 

[LD]

I''ve just found this and now I''m even more confused because the presence of fluorescence indicates Alexandrite:

What causes the color change?

Alexandrite is a trichroic gemstone which may absorb and reflect light differently in each of its three optical directions. However, it is not the trichroism that is responsible for the remarkable change. The color change phenomena is a result of the presence of chromium +3 ions and the way they are absorbed and reflected. In rubies the chromium absorption band is around 550 nanometers and in emeralds, the band is around 600nm. In alexandrite, where the band is at 580nm and right between ruby red and green emerald, the stone is balanced between them. When the light is balanced (daylight), the stone will be green but when the light source is reddish (incandescent), the stone appears red.

Alexandrite or Chrysoberyl, What''s the difference?

In practice, chrysoberyl and alexandrite may be difficult to differentiate. Since stones with a weak change may be called alexandrite and stones with a faint change are called chrysoberyl, what is the difference? Where is the borderline?

Since the origin of the color change in alexandrite is due to the presence of chromium while the color of yellow or brown chrysoberyl is due to the presence of iron, a close examination of the spectroscopy will reveal the differences as both chromium and iron display characteristic spectrums. The yellow variety shows a broad band centered at about 4450 A in the blue violet while the alexandrite variety shows a chromium spectrum. The presence of chromium lines in the red orange area of the spectrum are diagnostic for alexandrite.

Fluorescence is another property to help us differentiate. Chrysoberyl owns its yellowish color to iron and usually shows no fluorescence. The red fluorescence of alexandrite can be observed using the “crossed filter” method and it has been inferred that in border line cases the presence of a red glow and a faint chromium spectrum absorption spectrum would prove the stone to be alexandrite and not chrysoberyl.