Can't you track down some of the diamond dust things. I got a pack of 3 (coarse, medium & fine) for 7 or 8 quid at a a
hardware store. They look like a plastic sheet (different grades are different colours), 3 mm thick, & maybe 5cm by 15cm with a sparkly sheet of dust impregnated steel (with lots of oval holes) stuck to it. They're absolute dynamite, give a fantastic edge, don't seem to wear out, & seeing as your missus has against your stones, you could always stick to the "diamonds are a girls best friend" line... (unless you're not married, in which case I would advise never me