Europium is known for few things besides its extreme finickiness. Unless samples of this metal are prepared in atmospheres carefully purged of every last trace of oxygen you can expect at best dull looking bits the kind that belong on the greasy floor of an auto mechanic’s shop. A little more than that - and we’re really talking just parts per million - and you’re left with blackened crumbs.

So we were quite surprised when we got these domes. Whoa baby!! These are the rockin’ colors you’d expect of anodized niobium. Although totally unintended here, the two share in the nature of all those hues: a microscopically thin layer of oxides arranged evenly across otherwise unperturbed, flat metal which reflects light selectively. Dial in the thickness of this oxidation to a smidge either side of 500 billionths of a meter (or some 200 times thinner than a hair) and your eyes see blue. A little thicker, at 550nm, and it’s green. The whole of the rainbow, amazingly, can be encoded within the thickness of a frikkin’ virus(!). Any more or less and the effect is lost; less and you get no color, more and, yeah, greasy floor metal bits.

The color steals the show in this sample and now we’re going to task the lab that they better figure out how to make them like this from now on because that’s what the customer will expect going forward :-)