Engagement Ring Advice for Grooms

I like this advice from Jonathan at mymoney on how much money to spend on an engagement ring:

So, how much should you spend on it? My answer is very simple - Spend whatever you can afford to make your wife happy. That means both time and money.

My only modification to this would be to spend up to an amount that you can afford to make your wife happy. X was willing to pay more for a different ring. But I love the ring that we've selected together. And my ring size is a 4.5 - I found out.