One was a centenarian baker who was still earning ribbons at last summer’s Minnesota State Fair. Another was a state legislator whose esteemed political career was cut short by an assassin’s bullet.

For the indecisive among us, a trip to the nail salon can be mildly panic-inducing. With hundreds of hues lining the walls, the mental zigzag between pink, red—or should I go a little wild with orange ...