The chipped mug I keep using

It's a cobalt blue thing I've had since my residency—a small chip near the rim, smooth now from years of my thumb resting there. Most mornings I reach for it without thinking, and I'm not sure if that's habit or something closer to stubbornness. Today I noticed the chip catches the light in a way the rest of the glaze doesn't, and I realised I've never tried to fix it.