With two different colours and textures involved I would not be capable of pulling off something that would satisfy me, nevermind my wife.
I’d still rather try taking the rough edges off.
Have a look at Kintsugi, then find another mug similar to the favourite one and chip out a bit that is roughly the same size, use the files to dress both the chip and the mug, bond back together with gold epoxy, wallop.
That is way more work than I’m willing to do to restore a mug that is virtually indistinguishable from the one I got my wife when this one chipped.
I’ll post a pic later on to elicit some lighthearted derision for my efforts.
Have a look at Kintsugi, then find another mug similar to the favourite one and chip out a bit that is roughly the same size, use the files to dress both the chip and the mug, bond back together with gold epoxy, wallop.