It is called Rose of China. (H. rosa-sinensis)

Might I say it is very beautiful, love the color combination.

Thanks, Rozeluver! I was looking for the name of the particular cultivar. I found one that's vaguely similar to mine, called Delicia Amore, but mine has no red center, so it's probably something else.

Here is a link that might be useful: Delicia Amore

I think I found it. Jack Mantell. Very similar, at least.

Here is a link that might be useful: Jack Mantell