I think I would have cried. DS (who will be five in a few weeks) broke my favorite antique christmas ball this year, when we were moving. He knew he wasn't meant to touch it (it had been my grandma's) but he took it out of the box after I had packed it away so he could "see the light sparkle on it" as he rolled it...off the table

When he fessed up (just as I was unpacking it's special keepsake box in which he had stored the shards.

) i just was so sad.
I didn't scream or yell, I just cried. It was like the fifth thing in a month that he had searched out and "accidentally" broken or drawn on...I was just so sad. Since seeing me that sad, he has stopped completely. Maybe he wanted to know for sure whether breaking my stuff, even if he broke my heart, would change my love for him, and the answer he found was no, but he might make me really sad in trying. I don't know, but being honest and open with him about how I don't care about things, it's just stuff, but some stuff holds memories of people you love and as we move around a lot, I don't get to have a lot of those things, just really seemed to touch something in him.
I went through a phase of cutting holes out of the favorite clothing and things of my family right around when my parents started fighting (I was 6), either just before or just after they separated, I can't remember. Anyway, I had it in my head, maybe from Sunday school, that when you died you couldn't take anything with you to heaven, but I figured, they wouldn't make you empty your pockets, right? So I rationalized that anything you could carry in your pocket you could take in...so I went around the house and cut holes out of all my family's favorite outfits, just small swatches to remind me of them, in case I died (presumably until we met up again, or maybe I wasn't sure of the destiny of my loved ones,

who knows?

I was six!).
My sister was NOT impressed with my sentimentality, at all.

I think a good calm talk about why is a good idea, though the answer might be, I dunno.