Fruit jars have been made of glass since the 1850s.
The 1858 date on many jars refers to the patent date and not the age
of the jar.
Clear and aqua jars were common, whereas greens, blacks, blues, ambers,
and milk glass are rarer.
Fruit jars were also made of stoneware and can sometimes be found with
stenciling.
"PUTNAM 227" on the base of a jar with a smooth lip is a reproduction, but the "PUTNAM 227" jars with ground lips are original.
The best bottle show for fruit jars is Indianapolis, Indiana.