Great info everybody! Thank you so much! Well, looks like I am starting a quest for all the "like blue" vandas :).
I am going to look for blooming V. Tristar Blue or V.Patchara Delight at the show, which is only in April, sigh...
But to have some kind of action now I just ordered two vanda seedlings to join my little V. Bangkok Blue. They are V. Packchong Blue and V. Gordon Dillon Blue (although tag says "blue" in the last one, I could only find registered name V. Gordon Dillon).
I read that V.Packchong Blue can flower even on small plants...

Yes, but the metalloanthocyanins rely on the degree of oxidation and pH for their blue expression, as you said. They act like litmus paper in their colour expression and the same plant or flower can appear less blue (more purple) at higher pH.

Hydrangeas are a perfect example; blue flowers in acidic conditions and pink flowers in alkaline conditions. By changing the pH with aluminium sulfate or lime you can change the colour of the flowers on the same plant from pink to blue, back to pink again, year to year.

Therefore, I do not believe they are truly blue flowers as the colour is not stable regardless of pH.

Cheers.
Jim

Sorry, I think that I still have to disagree. ;) And I found a “Nature” paper showing that blue can go beyond the classic pH argument. To paraphrase, the same anthocyanin was found in roses and blue cornflowers, and up until then this difference in color was attributed to flower petal pH. However they have found that the anthocyanin in the cornflower is a very stable blue because anthocyanin molecules coordinate with flavone, iron and calcium to form a new supermolecular pigment, called protocyanin.

I’ll agree that there is no single simple anthocyanin molecule that is true blue though. there needs to be some complex chemistry for one to form.

Sorry to everyone for this excessively ‘science-y’ stuff.

Wy are you concentrating only on vandas? Ascocendas bloom more often and usually have brighter colors than the vandas.

Tucker, I like ascocendas too, it just seems that vandas have larger blooms, which I like at the moment. I am a beginner and only bloomed one vanda and it was Roberts Delight with enormously huge flowers. I was so impressed, that decided to get more of those.
When I found out that ascdas bloom more than once, I put Princess Mikasa on my list and got it.
I have few vanda species too (although not long enough to get them bloom for me yet)and got them because they offer variety in flower shapes and colors and many of them are fragrant.
Surely if I will see the blooms that I like - I will buy them no matter if they are vandas or ascdas or vascos, hybrids or species :).

I also wanted to ask about vanda flower shapes. Here is the picture of matured bloom of my V. Robert's Delight 'Garnet Beauty'. I saw many pictures of this cross(I think Cathy posted one here too)and their blooms seem to be flatter and more open, without those ruffled edges. Why mine never flattened? It is her first flowering. Or maybe because my indoor conditions are too dry? Do you have any idea?
Thanks a lot
http://2.bp.blogspot.com/-nBeoOG_5TG...ts_delight.jpg

Can you provide a link? I need to brush up on the research. Unfortunately my plant phys. is about 30 years old and has become rather dated.

My thing in university was improving heat tolerance in ornamentals such as campanula, lathyrus, papaver, and primula. Really wanted to work with gentians after my wife and I saw them in the Alps.

Cheers.
Jim

Phytochemistry: Structure of the blue cornflower pigment : Abstract : Nature There are links to the full text and PDF

You'll have to PM me your email address if that doesn't work, I'm not sure if it's open access. I can send you the PDF. I could get it via the university internet network.

I did more reading and discovered that you are correct as well. Sorry about that. While these complex molecules I mention above are responsible for blue in some flowers, in others it's due to chromophores and pH, so reflection of light, like you were saying.
This explains both mechanisms: Anthocyanin chromophores and the quest for the blue rose and the link to a paper cited here. Blue flower color development by anthocyanins: from chemical structure to cell physiology - Natural Product Reports (RSC Publishing) This one is especially interesting, it goes over all the existin knowledge on what makes blue!

Orchideya, have you read any books about Vandas ?
In "Vandas and Ascocendas and their combinations with other genera" by David L. Grove you will find a lot of info about the orchids and there is also a chapter about the standard for the flowers.
Martin R. Motes book "Vandas" is also a "must read" to learn everything about them.

Cool! I saw the one on the quest for the blue rose. Interesting reading.

I'm looking forward to reading the others.

Cheers.
Jim