In all the pictures I've seen of songwriter/singer/producer Andrew Marlin, none of his mandolins are orange. They seem to have a natural finish or glossy black — certainly nothing the color of a Halloween pumpkin.

I mention this because, as Marlin is the mandolinist in the quantifiably fine North Carolina bluegrass/roots duo Mandolin Orange, well, I think he's A) missing a great endorsement possibility by not getting his sponsors, Sullivan Mandolins and/or Gilchrist Mandolins, to custom build an orange instrument; and B) setting fans up for aesthetic disappointment when they show up at a gig and his mandolin is wood-colored or whatever.

But we'll see, won't we? Mandolin Orange — Marlin's bandmate is multi-instrumentalist Emily Franz — performs Friday in Westerly at the Knickerbocker Music Center. If you're unfamiliar, Mandolin Orange features pastoral, intertwining vocal harmonies on tunes like "Such Jubilee" and "Wildfire." Theirs is the sound of mountain music easing into the future with wide-eyed joy.

Mandolin Orange with guest Chrissy Stewart, 8 p.m. Friday, Knickerbocker Music Center, 35 Railroad Ave., Westerly; $25 advance, $30 door; (401) 315-5070, westerlysound.org.