Designing materials from scratch to produce blue is difficult even today, Subramanian says. "So much chemistry has to come together," he says. Subtle changes in the arrangement of neighboring atoms can throw off the energy levels of an atom's electrons, altering the color it can absorb. The red of rubies and the green of emeralds both spring from chromium ions surrounded by six oxygen atoms; other atoms in the two stones cause the color difference by altering the chromium's energy levels. Such effects are very hard to predict, Subramanian says: "If rubies and emeralds did not exist in nature, no one would know how to create them."
But scientists have not given up hunting for new blues, continuing an age-old quest with 21st century tools. Although Subramanian's discovery came about by accident, other researchers are methodically using physics, chemistry, and genetics to find or create new blues for painters to dazzle with, edible colorants that make food more interesting, and blue flowers that, so far, only exist in artists' imaginations.
@Kam-Yung Soh Read this last evening, but too tired to post comments at the time. Really interesting piece.
Who would suspect that blue would be so difficult? In retrospect, though, it would have to be, or nature would by now have produced lots more of it than we see occurring.
Someone once told me, "There's no such thing as blue food." It was a reference to what nature has managed to produce on its own, and is true enough, I think, because even blueberries aren't actually blue. In any event, it was probably a subtle indication that producing true blues would be difficult. Such has proven to be the case.
I always wondered why there aren't many kinds of blue foods ... is this really the reason? Or is blue rather not as well suited for fruit that plants intend animals to eat? ... maybe because the colour contrast blue-green isn't as stark as red-green?
@existence.is.the.proof The article matches what I learned at university, so I think this is still the correct explanation. From the article: “Animals such as the morpho butterfly and the blue jay appear blue not because of a pigment, but because their feathers or scales contain nanostructures that reflect light in a way that cancels out all but the blue wavelengths. … Plants have evolved many classes of pigments: Chlorophylls color leaves green; carotenoids come in orange (carrots), red (tomatoes), and yellow (maize); and betalains produce the red color of beetroot. But only one class of pigments is capable of producing blue: the anthocyanins. (The word literally means "blue flower.") And even most anthocyanins are not blue but red, because they naturally absorb blue light; only if the plant tacks on chemical groups can the molecule shift toward absorbing red.”