Royal Blue Potatoes This page first published: Apr 8, 2005 · Updated: May 12, 2018 · by CooksInfo. Copyright © 2021 · This web site may contain affiliate links · This web site generates income via ads · Information on this site is copyrighted. Taking whole pages for your website is theft and will be DCMA'd. See re-use information. Royal Blue Potatoes are oblong, with purple skin and yellow flesh. Cooking Tips Best for use in salads and as a boiled potato.