i accidentally caught a bit of This Morning one day last week where a diamond expert was on the show.
he said to get your diamonds gleaming drop them in a bit of vodka for half an hour.
well i just poured half a shot into a glass and dropped my very grubby diamond rings into it - (i own 3 but wear them all the time - they are not flash!)
and i can confirm this works. well.
my diamonds are lovely and sparkly again! just thought id share for the greater good!