I found this topic on the China History Forum, some guy was able to do this to a 2,000 year old Han Dynasty jian.
Click here
Amazing isn't it? Well what I'm left wondering, is how does one know how far you can restore an ancient or medieval sword? I remember seeing an antique Han sword being sold for about 150 bucks on SFI awhile ago, it had turned completely green but the sword itself was in pretty intact condition. I kinda wish I bought it now that I've seen the results of this restoration.
And of course all those really cheap khopeshes rusted completely green out there, and then all those Viking swords and stuff. Also how is this kinda restoration done?