Being a machinist I used diamond stones ( Diamond Machining Technologies) decades ago for sharpening tools. It was natural if I could sharpen machine steel these diamond stones make sharpening my Gerbers very easy.
http://www.dmtsharp.com/
I have a med grit bench model in a kitchen drawer along with a fine diamond straight steel. I have a double sided folding model Med/fine in each of my day and freighter packs.
Now all the fish cannerys and fisherman have any number of these products handy to either sharpen or stand up an edge. These sharpeners have become very popular here the past 10 years with the above mentioned website products easily the standard here.
FYI
Neal