Those blue mason jars were mass produced until 1937 using sand from around Lake Michigan. It was that sand that gave the glass its blue hue.

When did ball stop making blue jars?

Blue glass Ball jars were produced in the late 1890s and early 1900s, but the company stopped producing these in 1937.

What is the difference between a ball jar and a Mason jar?

A Mason jar is a molded glass jar that is originally used in canning to preserve food. Other common names for the original Mason jar include Ball jars (after the Ball Corporation), fruit jars and simply glass canning jars. All Mason jars are not created equal.

Are Ball Mason jars toxic?

Almost all of the newer Ball Jars that I have tested have tested NEGATIVE for Lead or Cadmium. These levels found here in this jar that I tested (picture below) are trace/ very low/ negligible and are not likely to be leaching at all. Newer clear glass is still likely the best thing to store your food in.