[header] How to buy an engagement ring [title] Find out your what kind of rings your intended fiancée likes. [step] Knowing the styles of engagement rings she prefers will help you narrow down the vast list of possibilities. [substeps] If you want the engagement to be a surprise, pay attention to her comments on rings she sees or when other friends get engaged. 
Ask her friends if you're not sure. They will often know the styles she likes or exactly what she wants.