I buy those for my (old Canadian size canning jars that aren't made anymore) Gem jars.ORChick said:Great find! Lucky you!
I have found the rubber rings for the old glass top jars at a local hardware store. Its a Canadian company - Viceroy Rubber and Plastics Limited. I have a few of those jars (just a few, alas!), and also use them for dry storage.
The Gem rubber rings are 78mm, are these the same size as your jars or are yours standard regular/wide mouth jars? If they are standard mouth jars you could always get the rubber rings from Tattler