In order to determine an antique Mason jar's value, use a reference guide such as "The Redbook of Fruit Jars." Factors with a significant affect on a Mason jar's value include the date of manufacture and whether or not it has the original lid. If the jar has a spelling mistake in the embossed writing, it may be rarer and more valuable. Some jars have rare forms of closure that make them more valuable.
The jar's age is a major factor in determining its value. To date a Mason jar, look for indented rings and pontil marks at the jar's base. These marks indicate that the jar was made by hand by a glass blower. Machine-made jars became more common after 1915, and they have a seam that runs up the jar's sides.
The Ball Brothers Glass Manufacturing Company embossed its logo onto its jars in a variety of styles throughout the 19th and 20th centuries, so collectors can date jars by examining the logo's typeface. If the jar has the word "Ball" embossed on the side, it is a product of the Ball Brothers in the United States. The letters "BB" overlaid with a "C" and an "M" indicate that the manufacture date was between 1885 and 1886.
Unusually shaped and sized jars may also be more valuable. Pint- and quart-sized jars are relatively common, but larger sizes may be rarer. The same is true of square jars, which were never as popular as round jars. An old jar that is in good condition may be worth considerably more than one that is cracked and chipped.