I'd try vinegar if you haven't already. But the denture cleaner, as one mentioned, seems like a possibility too.
You might try Barkeepers Friend, don't know if it'll work or not, but it's worth a try. Also, there is a product at the auto store to clean headlights - but it's probably made for plastic. Depending on the emotional value, it'd probably be cheaper to buy new jars.
Or try soaking them in soapy water with a little ammonia. Leave the house while they soak. If they are etched, this will not help. By soapy water, I mean regular dish detergent, preferably Dawn. It gets out/off a lot of stuff other soaps won't.
They probably have what is called "etching". It's usually caused by washing in the dishwasher - usually from soft water & too much detergent. This will not come off. So you either have to live with it or buy new jars. Sorry.
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