I bought a Hi Tech Diamond lapidary polishing machine with numerous grade diamond wheels for just that purpose, cleaning and restoring odd sized crystals. It's very much a time consuming endeavor, and I've found that the vast majority of crystals are easily replaced with generic mineral glass. If you have a crystal that is scratched, and you can feel the scratched area with your fingernail, then it is going to take quite a while, and a number of different wheels, plus cerium oxide, to get it back to perfect. What I'm saying is that it just wouldn't be worth the time in my estimation, unless you were doing the work yourself.
I have dozens of 330W18GN crystals taken off original Pogues over the years that are in need of a polish. If there is anyone out there willing to do it for say $30 a crystal then it makes economic sense.
Adrian at Vintage Time Australia (VTA) has a guy who does this for him. The guy restored my chrome-rimmed super early Pogue crystal since polishing was literally the only way to have one. You can't tell it isn't brand new.
You could send me one of them if you like. Make it an extremely bad case. I'd gladly give it a try. I've brought a few back to near perfect, but, as I mentioned, the majority of the watches I restore have readily available replacements. If I can't get yours back to 90-100%, no charge.