Everyone breaks a glass from time to time. There's usually nothing to be done about it but sweep up the pieces, mourn the no-longer-matching set and resolve to forgive whichever person knocked it over this time--but that's not always the case. Sometimes even glass can be repaired. It requires expert attention and that means it doesn't come cheap, but if you have antique pieces of heirloom crystal you've inherited from generations before you--or an expensive luxury wine glass set bought for you as a wedding present--it's well worth looking into.
Breaking a glass isn't the only way to damage it, either. If you've got anything made of glass that is special to you and that you worry about the potential demise of, read on to find out what you could do if it became damaged.
SCRATCHES AND STAINS
Have you ever seen a piece of antique glass that, while not chipped, is so worn that every edge looks white? Over time, glass will dull and scratch no matter how well you look after it--especially if it's in use. Polishing it yourself at home delays the inevitable, but sufficiently old glass will probably need the attention of a professional at some point. Many glass repair services will be happy to offer you a 'glassware MOT' if you ask them about it--they'll look your pieces over, deal with any minor problems, polish them up to a high crystal shine you can't get at home and send them back to you looking good as new.
CHIPS AND CRACKS
Glass that is chipped at the rim or has a couple of tiny cracks is also a pretty straightforward repair job. For chips, your renovator will simply use a crystal file to even out the rim of the entire glass to below where the deepest chip is--and then polish the whole thing till it shines so you can't tell there was ever any difference. Stood side by side with other glasses from the service you might be able to spot that one is a little shorter than the other if you're looking for it, but it'll never show at a laid table and nobody who hasn't been told will notice. To seal cracks, your renovator will use a special glass sealant to fill them in and then, once it's dry, buff the whole glass back to its original shine.
BROKEN COMPONENTS
Glassware can suffer plenty of small misfortunes. Glass candle holders very quickly crack if the candle is allowed to burn down so far that it heats the bowl; the stems of wine glasses are highly likely to break during a house move if the glasses are not packed with extreme care; the stopper of a decanter is extremely easy to drop after a glass or two of the port inside it, and it could well smash if it lands on a marble kitchen floor. While not even the experts can piece broken glass back together and have it good enough to use at the end, there are ways to re-create certain components and replace them so subtly nobody will be able to tell they're not part of the original. A good renovator will take extreme care over ensuring their replacement components are identical to what they're replacing in every possible way--so if your piece is part of a set, make sure you also take them an unbroken one they can copy from.
TOTAL RE-PURPOSING
Sometimes, something simply can't be fixed. That needn't be the end of the piece's life: if it's important to you and you want to keep it around, try talking to a glass specialist about having it re-purposed into something else. Whether it's turning a decanter into a vase or a sherry glass into a votive candlestick, there's bound to be something that can be done.