There are two reliable restoration artists I know of and use in the USA, Andrew Najarian of High Polish Studio in Tennessee and Ed Poore of the Crystal Workshop, Maine.
Note, be aware that turnaround time can be rather lengthy sometimes months, so don't send off weights you will be needing soon unless you want to pay a large "fast turnover" surcharge.
PS: -> Anne, yes, I did see the extension warning, but tried it anyway, my error.