In your opinion when the engagement ends in a breakup

Legally I believe she has to give the ring back to the man. I was reading on Wiki that when they become married it then becomes the property of the woman, but before that it's his property. Now, as for other jewelry if it's given as a gift for a holiday (birthday, Christmas, Valentine's day) it's automatically becomes her and is her possession. Check on Wikipedia under Engagement Rings.

In my opinion, regardless of who gave and who received. It is but proper that the girl should have it if she wanna keep it. Out of respect for whatever you both shared when you were both in love. And I also think that a guy should always give way to a woman. XD

the one who give sit. It will have no meaning then. so its better to return it back

i dont know... maybe it is up to them to decide. there can be some cases when none wants the ring as it will remind them where they have gone wrong. however, there are also cases where the person who caused the breakup will have the ring... so, i guess it depends in the situation.