The headstocks of every Ridgewing development prototypes from 2015 had the same streaked-ebony veneer with a custom dragonfly inlay created by Precision Pearl of Austin, TX. I have put in my time over the years cutting pearl and abalone shell inlay for headstocks and fingerboards, and I have breathed quite enough of that rotten-fish-smelling fine shell sawdust. So now I leave it to the experts, and gaze in awe at the beauty of inlay made by CNC. (By the way, Precision Pearl was great to work with, and I highly recommend them).

In the summer I am entranced by dragonflies. These seemingly-cute little guys flitting around at twilight are actually perfectly-designed aerial hunter-killers, whose behavior, if scaled up to human size, would be the stuff of extreme nightmares. But dragonflies are also extraordinarily beautiful in their coloration, colors the stuff of dreams.

Those big composite eyes and the iridescent colors dancing on their face and body and wings floor me, and give the distinct impression that a superior intelligence is looking at me, perhaps judging me for a meal. Sorry, way too big.

The iridescent colors of the domed eyes and body are created by micron-scale optically reflective layers within the surface cuticle, which create colors through optical interference. A particular interference color corresponds to a particular layer thickness. The reflective interference of a thin layer yields a shorter wavelength “blue-er” color than thicker layers, which will create a longer wavelength “redder” color.

The correspondence between interference color and reflective layer thickness is mathematically precise, such that interference colors can be used as a kind of ruler for measuring micron-scale features by eye.

Here is a picture of where an elder car was recently parked, and a drop of its oil had landed on the wet pavement.

This oil drop has been here long enough to spread out so far as to separate out into successive color bands that fade off to nothing along a fractal-like silver border.

The color bands have a physical meaning. The outer-most silver color corresponds to a thickness equal to a single molecule of the oil, which is a carbon chain with roughly 15 atoms.  The next color band with the gold color corresponds to a double -oil molecule thickness. The silver and gold areas are too thin to create interference colors.  As we move toward the center of the oil stain, can be seen to march right up into the visible light spectrum starting with violet, then blue, green, yellow and red. Then the whole color sequence repeats as interference layers overlap. At the center, where we might have expected to see some kind of maximum condensed color riot, is instead a small patch showing just the wet pavement, without colors. Hmmmm….

So what do oil spills have to do with dragonflies? Well, note that the optical layer in the dragonfly cuticle has the same thickness as a particular color band around the oil drop.

Which brings us back to the headstock dragonfly inlay.

In the inlay, the dragonfly and its wings are cut from white pearl, while the water ripples are cut out of green abalone shell. As you move your head back and forth looking at them, the colors shift and swirl in the smallest details. Magic stuff.

Why does our eye find this iridescence so captivating? Why do believers describe the gates of Heaven as “Pearly”?