Like two disparate instruments twining their melodic lines in blissful counterpoint, building up in rippling progression to that glorious moment of harmonic perfection that makes you want to cry or dance or hug someone...
A little like that. Here's the bare bones of the matter:
Complimentary pairings create the highest tension and excitement, but this one is tempered just a little with complexity.
Coppergreen is a cool jewel-toned turquoise blackened by weather and accompanying minerals, yielding rich and earthy base notes of black-glazed bluegreen. Copper on the other hand, is a hot and highly saturated colourway, falling primarily in the red-orange zone, but with overtones spanning a range from gold to fuschia. The desaturation of the bluegreen and the broad base of the copper hues takes the potentially strident edge off the duet, giving it harmonic stability.
The pair could be the joyful accessory to a dignified ensemble, or a glorious accent on a Coppergreen cardigan. As for all-over sweater patterning.... well, for those with an unstoppable joie de vivre, why not?