Some wag on the MYBR forum suggested this.. to a question “Correction there GT_guy, all the anodized Zaskars did not have a rough texture to them......in fact none did......all of the anodized Zaskars were ball burnished (polished appearance) before being anodized. There is a difference between ball burnishing and polishing. Ball burnishing is done with ball bearings and actually helps to harden the outer surface of the finished frame and it also holds the luster longer than just polishing naked aluminum. GT made the Zaskar in a number of ano colors over the years. Ink blue, Anodized Turquoise, Red, Black, Purple Fade. There were a number of colors done as samples that were stamped BLEM before the size on the dropout as well. I have one of those in a solid medium blue ano finish. I've seen them in orange, green and other colors too. But all those were done as samples.”
I have no idea if it’s correct or not but the latter for a non original bike sounds interesting?