my microplane hand grater literally did the job this afternoon -while trying to slide the cover off mine, i grazed my thumb against the grating slits & it took off the top layer of skin. there wasn't any bleeding, but it's pink, raw, & stings.
(if you're looking for a grater/zester, i highly suggest buying microplane. it's a little more expensive, but a great kitchen investment.)
after cleaning & wrapping the wound, i had to put a cover over my thumb so i could continue working (i was in the middle of working chef berger's recipe of pear pudding. it smells like christmas.). the cover looks exactly like a condom & is rolled onto the finger like one as well, except it's 1/2" in diameter. i felt like i was in health class, practicing correct condom use on a banana.