Do you need an engagement ring *and* a wedding ring?

Do you need an engagement ring *and* a wedding ring?

“I’m thinking about buying one ring that can be used as an engagement ring and as a wedding ring. I don’t want to spend too much so we can have money for important things, but I don’t want to be cheap either. I read some people are starting to do this.
Is this smart, or should I split the money between two rings?”