An interesting read on the color variations:
“Out of all of the Hawaiian Islands, koa grows predominantly on the Big Island,” says Chris Allen of Koa Wood Hawaii in Kurtistown, Hawaii. “By state law, you can not cut down live koa trees and there are just not enough of them on Oahu for harvest. At the low elevation, the koa tends to be real blond and not have a lot of color or character to it. That’s why the Big Island has the best koa. And Maui has nice koa, too, but again, not as much.”
Does anyone play a Martin with a pickup?
Every Martin C1K (and the tenor T1K as well) I've seen have been much lighter coloured than the typical Hawaiian made ukes. For some reason, Martin ukes made of koa don't have that reddish tint to them that's typical for many other koa intruments. It makes them a bit plainer but also somewhat distinct, in my opinion. I like them quite a bit.