My question has been pending on the message board for quite some time, with nary a single reply. Surely someone knows how to distinguish blued paper from blued paper from the white paper period?

This question has puzzled me for some time. How is "blued paper from the white paper period" distinguished from "ordinary" blued paper? The question was raised again in my mind by lot 324 in the June 5th upcoming Spink auction. This lot is described as an unmounted unused 2/6 lil...