The final two categories are arguably the most attractive and also the rarest, meaning that glasses bearing them are the most highly sought-after.  Enamel-labeled shot glasses are really the fore-runners of the more common 'etched' variety.  The label was hand applied and stands well proud of the glass surface. It was also embellished with pastel colors and gold curlicues above and below the applied enamel. These refinements seldom survive intact.  Enamel labels are very familiar to the bottle-collecting brigade because many bar-back decanters and bottles were branded in the same way.  

'Elk Club' is a brand that was registered by Mayer & Sons, of Philadelphia, PA. in 1893, but the glass was probably produced for Rheinstrom Bros. of Cincinnati OH.	'Kriskrinkle' from Rheinstrom Bros. of Cincinnati OH.	'Old Windsor Club' from ... you guessed it... Rheinstrom Bros. of Cincinnati OH.