Topic: Alexandrite Bird Bowl, Why green?

[svazzo]

Hi everyone,
I know this has been discussed before, about Alexandrite glass, but what makes it turn green?
I have a few other pieces that turn light blue, but haven't really had 1 that turned green before.
Could it be because of the pink that is also inside the bowl?
This is not for identification, i know it is Murano, but wanted to know what to put in the description about the change to green.
Thanks!

Javier

[johnphilip]

 Is That Alexandrite or Alexandrit i believe there is a differance. JPH

[David E]

Neodymium changes colour between lilac and pale blue. Other rare-earth elements react differently.

One often quoted article:
http://www.mindspring.com/~reyne/neowhatsis.html

[johnphilip]

  Webb made a type of glass called Alexandrite if my memory is still intact i think it was ruby graduating thru several shades to lemon it is quite rare and expensive.The several pieces of Moser dichroic i have had were marked Alexandrit.no E on the end.

[David E]

Yes, you're right JP - Webb did produce Alexandrite, but I think there were many other makers using this term as well.

Search for alexandrit* here:

http://www.glassmessages.com/index.php?action=search

[svazzo]

Thanks for the replies!
So what do you guys think?
The bowl does look a little more pink than blue on the body, but the head does look light blue.
Maybe it is this other type of Alexandrite glass johnphillip just mentioned?
I am now more confused than ever, lol. But its great to hear this new spin on the topic.
I didnt know it was also made to turn a lemon color.

Javier

[Frank]

Webb's Alexandrite is a colour that changes when 'struck' (=reheated) and has to changes. It is ALSO a dichroic glass in that the colour changes due to incidental light (Modern coatred dichroic) or transmitted light. The latter for Webb's Alexandrite and it is not particularly affected by light source.

What you have is colour changing under different light spectra. e.g. Neodymium (In my opinion the article David quotes is wrong in describing Neodymium as dichroic, but than words do get re-purposed all the time, more to do with what gets published rather than right or wrong Using dichroic to describe colour changes due to light source is ridiculous as dichroic means two colours and spectral colour changes are certain to give more than two.

Neodymium absorbs yellow/green parts of the spectrum and as that is the main component of fluorescent light is naturally has a dramatic effect on it. It can also be used in low proportions to improve the clarity of green tinted glass without any colouring effects, no doubt some difference would be visible under fluorescent but possibly invisible.

Other rare earths or oxides are used in glass too and one that absorbs red/blue could be responsible for your yellow colour, maybe titanium, erbium or yttrium.

[johnphilip]

Thanks folks i thought this would start an interesting chat and clear up a few points has anyone pictures of a webb Alexandrite piece it would be nice to find out a little more as i have read about them but never seen one.JPH

[David E]

Bernard has mention Webb's Alexandrite before, but I'm not sure if he has an example.

[Frank]

If you search for Alexandrite in the forum, you should find the topic started by Jim Sapp. This included images of one example.

I have handled a few pieces, it is a very light fine glass and the dichroic effect only shows on the rim giving a rich chocolate brown colour when held at the right angle. The struck colouring is also exquisite.