Either Manchester City or Wigan will be taking it home on Saturday, so the FA wanted to make the 132-year-old pot look as good as new.
London silversmiths Thomas Lyte are paid a fee every year to look after the trophy, but the bill this year came to around £3000.
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"Silver is a metal and if it sustains a knock here or a bump there, it can pick up little dents and creases. Fortunately, you can reverse that damage with care - it's a bit like panel-beating a dent in your car, except the process is more delicate.
"This year it took probably 70 to 80 hours of restoration and polishing, where you would normally allow more like 38 hours to make sure everything's all right.
"I've been looking after the FA Cup for about 17 years now, and the damage this time was more extensive; although a few years ago, without naming the team responsible, the Cup came back with the lid in two pieces."
It is not the first trophy that Chelsea have damaged. The handles of the Champions League trophy were broken, and Thomas Lyte silversmiths brought that back to life too.
Williams added: "We did actually do some restoration on the Champions League trophy."