Subject: Why does red wine or blueberry juice turn blue when diluted with water?

I've noticed that when I run water into a glass in which red wine has dried, the 
dilute wine is red at first, but then as I dilute it further, it turns blue. Same 
with the juice of frozen blueberries -- it's red when concentrated, like what's 
left in the pan after I cook 'em to put on pancakes -- but turns blue when 
diluted. When it's red, I'd say the dye particles are absorbing blue, and 
scattering red back to my eye. When it's blue, I'd say the dye particles must be 
the right size to scatter blue by Rayleigh scattering. But why should the 
dilution make any difference? Why isn't it always one or the other?

Re: Why does red wine or blueberry juice turn blue when diluted with water?