Just prior to the introduction of the star designation in the early part of 2000, NGC introduced two designations designed to inform the buyer that the coin was completely toned "T" or completely untoned "W". Unfortunately these designations were not widely accepted by the numismatic community and were discontinued on 8/1/2002.

Since the designations were only used for 2.5 years and were discontinued a decade ago, it stands to reason that many collectors might have never seen or heard of a coin bearing either of these designations. I don't know whether these designations by themselves drive a premium but in my experience, they are exceedingly rare. In fact, I only own one "W" and two "T" coins. The "T" designation was used on almost all of the Appalachian Jefferson Nickels which were also slabbed in the NGC generation 8 holder that was only used for a 4 week period spanning August-September of 2000.