The number on the bottom of a Mason Jar means and refers to the mold number.
The mold number on the bottom of the Mason Jar means and is meant to tell you where the mason jar was positioned on the glass-making machine that was used to produce it.
Many Ball mason jars have a number printed on the bottom of the jar, but this is a mold number that does not indicate the year of production.
Some ways to tell how old a Mason Jar is include.
Pontil marks or indented rings in the bottom of the jar mean it was hand finished by a glass blower.
Seams also help determine the age of your jar: Seams that go all the way up the jar indicate it was machine made, probably between 1895 and 1915.
Color can also help date your jar.
If you have a jar with one of the older logos, it will likely be worth more than one with a newer logo.
Next is the color.
Clear and pale blue are the most common colors, but jars of all colors were produced.
Yellow and amber jars were common.
Some of the most valuable Mason Jars are.
Van Vliet Improved Jar – $23,500.00
Black Amber Magic Star Fruit Jar – $3,000.00
1933 Ball Upside Down Error Jar – $1,000.00 There are two types of Ball upside-down Mason jars.
The 1870 Chief Mason Jar – $800.00
1858 Willoughby Stopple Jar – $500.00