Hi Sally
As Wee Al says, jeweller's rouge will probably sort you out, so long as the scratches are not too deep. Available from all good jewellers.... lol.... I would ask in an independent jewellery store first, they are more amenable to unusual requests like this ! You just have to rub a little of the very mildly abrasive paste onto the scratch and hopefully it will fade away ! If that doesn't work, ask in the jewellery store if they know of a good glass merchant who can replace the glass top for you.