The final two categories are arguably the most attractive and also the rarest, meaning that glasses bearing them are the most highly sought-after.  

Label Under Glass: If ever there was a holy grail among pre-pro collectors, a label-under-glass glass is it.  'Label-under-glass' refers to a specific technique whereby a label was applied to the outside of the glass and then a thin layer of glass was applied over it to seal it in place.  Such labels can be found on the outside of the glass or often in the base, so that the label is revealed as the imbiber drains the shot.  Words and pictures really can't capture the appeal of these glasses.  Although the technique was used in conjunction with perhaps 40 or 50 different brands, they're so appealing and rare that they're highly prized among pre-pro collectors.

'Old Harper Whiskey' from the Berheim Bros, Nelson Co., KY	Looking down the barrel of 'Tippecanoe Whiskey'	A label-under-glass shot advertising 'The Wm. Foust's Sons Distillery, Glen Rock, PA'.