How can I convice my boyfriend to not give me an engagment ring?

I simply don't want one. I like the look of a single wedding band with some diamonds in it. But he feels this is an insult to his masculinity. Like he has to brand me or something, in order to be planning a wedding. What gives? Guys don't have to wear rings till the wedding. Anyone else feel this way? Nothing against ladies who love their rocks. To each their own.