Hock is the old-fashioned term for German white wine, so any wine glass specifically made for this wine is a hock glass. Typical examples have unusually small bowls and are therefore unsuitable for really enjoying the aromas and tastes of good German wine. The best glass for "hock," as for any non-sparkling wine, is a large-capacity clear glass that allows you to see and swirl the wine.
They Were Once Big
In "How to Enjoy Your Wine," Hugh Johnson noted that hock glasses once held 1/4 liter (about 1 ½ cups) of wine. This may have been thought a "fair measure" because German wines were not high in alcohol.
Small and Pretty
More recently, the typical hock glass is long-stemmed and has a small cup, sometimes lavishly cut or engraved. The bowl is sometimes brightly colored.
Colors
Hock glasses traditionally have a clear bowl but a tapered, ridged green or smooth brown stem. These colors will disguise the color of the wine--their intent may have been to make it look darker and therefore older and better.
French, Too
Alsace, in eastern France, also makes white wines from Germany's riesling grape. Alsatian rieslings were also drunk in brown-stemmed hock glasses.
Why a Hock Glass?
German wine writer Jens Priewe thinks that fancy hock glasses date from a time when wine was an expensive luxury. The unsuitable but pretty glasses were meant to be displayed more than used.