I have a Masons Jar with a Ball Dome lid in blue-green. It has a circle and a keytstone within the cirlce. The jar has bubbles in the glass but otherwise is in excellent condition. Would anyone know the value of this Mason Jar. It also has a number 40 on the bottom of the jar.
You don’t say what the color is. That is a patent date. That does not mean that your jar was made in 1858. It could of been made in 1958. A few years ago those type of jars were a dime a dozen. Now they have become a hot item, They are being used for crafts and even table decorations for wedding receptions and now everybody is back to growing gardens and canning has become popular. recently at an auction green or blue mason jars were selling for $16.00 each. Half gallons were selling for $36.00 each. They also are a hot item on E-Bay even the old screw type lids and inserts. If it’s clear glass the value might be a little lower.