How to break the news of my belly piercing to my mum?

I turned 16 almost exactly 3 months ago, and almost 2 months ago I got my belly pierced without my mum's consent or awareness, but I can legally consent to it being done myself.

Before I got it done I'd been wanting it done for at least a year, so it wasn't a rash decision. I checked out the piercing place before; reviews etc said they're really good, friendly and make everything easy and sterile and all that (and they lived up to it when I went in).

So it's been almost two months and my mum still doesn't know, how could I break it to her that I've got my belly pierced? I was thinking of waiting till it's more healed, then going out, coming back and saying "Mum I got my belly pierced today!" and I'll pretend that it's just healing really well.. Any better ideas?