What was the original color of St. Patrick's Day?

Though green is the color that is most famously associated with St. Patrick, this saint's original color was actually blue. Evidence of this can be seen in paintings that show the Catholic saint in blue vestments, or robes, rather than green.

Not only was blue St. Patrick's color, it was also Ireland's color as well, with the 16th century Irish flag figured as a gold harp on a blue background before it was replaced with a green harp flag. St. Patrick likely came to be associated with green as Ireland itself did, which occurred gradually around the 17th or 18th century.