argghhhh glass in the microwave..............it should be alright! But be warned if you heat it to excess.....say 3 minutes in a 700w machine.....you will open up a tear in the universe, not huge like, probably big enought to put your hand in or a squash ball! Now once this has happened you'll be thinking '' how do i stop it tearing!!!? OR do i just leave it, smear it with toothpaste and hope no one finds it.'' You'll go with the toothpaste and for three weeks you'll feel great "yeah my toothpaste plan worked" you'll be saying!Then you''l go out get drunk one night, return home and want a snack. You'll make a peanut butter sandwhich, with some crisps,a slice of lemon all soaked in gin in it and you'll heat it up in the microwave. The gin fumes erode the toothpaste, tear gets bigger, world collapses! and i think you would find all this information in the MICROWAVE Manual, if you hadn't thrown it straight in the bin. This is all a 100% thruthful as far as i know, i think, don't quote me though. I don't want to get sued by some family in costa rica for tearing holes in there house!