A friend got engaged a few weeks ago. Her fiance bough her an antique ring they came across while vacationing upstate. She loves it. It's very deco and unique and when she took it to her local jeweler for sizing he told her that it was not an engagement ring. Her sister said the same thing.
Your engagement ring can be anything you want it to be. It can be a colored stone instead of a diamond. I even know two women that chose rings that are more in the style of an eternity band than a traditional diamond engagement ring. And you know what, their rings are lovely and what's more important is that they love them.
You are the person that has to wear the ring daily and it's a gift from your future husband, so pick a style that reflects your personal style and tastes. It doesn't matter if others do or don't like your engagement ring as long as you do.