It completely depends - what kind of jewelry, what bag, who's paying, if there is an occasion.
I'm getting an upgraded engagement ring for my 30th birthday. Sure I could have asked for a new bag to the same value but the ring is hopefully something I will wear forever. The bag would be loved and all but it's not in any way the same.
But if I was talking about maybe a bracelet or a necklace that I might wear occasionally rather than a bag I could use every day and really wanted, I'd probably go for the bag.
I know my husband would be a bit put out at being asked for a bag over diamonds. He considers the jewelry to be much more of a gift than a bag.
But I also never buy my own jewelry whereas I always buy my own bags!