How do I cover a broken piece of an oval shaped mirror?

A photo would help. Is it the frame? is it wood or metal?

need more info , picture or something. Sorry can't help with just this much info.

For safety reasons, I would remove the mirror, take it to a local glass shop and have a new mirror cut. It is not that expensive. Much cheaper than a doctor or ER visit for sutures. Maybe not too creative, but good sense!

Bust it all and make it a mosaic. lol

If there was a backing of wood then I say glam it up with clear and metal beads that you glue there but maybe also do the entire rim at same thickness of that area or if not then just do the opposite area of mirror. If there was nothing behind to hold beads then see if you can add something to area such as wood but very thin so as to not interfere with opening and closing. If not able to do that then glam up entire mirror and make it look like it's the design. You can out line the entire mirror following that shape or do your own thing but I think that this will be the least expensive and it will be fun. Look on line. But I have Seen this and it looks so neat I'm thinking of doing this to my 80's mirror that takes up entire wall I plan on taking it down to have it professional cut for my 36in vanity then put up shelves in floating glass style since it's a weird original design. Once I have mine cut since it is just a mirror I have been thinking about how I want to add beads. I don't want to make it too feminine since I have a husband. And for re-sale in future. I think I saw it on this site type it in mosaic mirror.