This was a long time ago but I still feel a bit guilty, so I guess that must tell me something.
Having a cup of coffee at a good friend's house and I accidentally dropped the mug after washing it out and it smashed.
Friend then told me it was a special mug, so I looked it up and the replacement cost was, in today's values, over £50.
She used that mug because she never washed up until all the mugs in the house were in the sink dirty, not because she thought it would be nice for me to have my coffee in it.
I wouldn't, personally, have given it to a friend for exactly the reason that happened.
She never asked for me to replace it, and I didn't.
AIBU - you should have replaced it without being asked
AINBU - she shouldn't have given me the mug if it was worth that much and a sluice out of a 50p mug from the sink would have taken less than a minute.