Buying stones loose and having them set is a great way to save on engagement rings. In purchasing the stone separately, you can save between 10-25% when compared to a preset engagement ring. Diamond wholesalers can also help you in selecting a stone to fit your budget.
Use a slightly smaller diamond for her engagement ring. A diamond that weighs in at 0.95 cannot be visually differentiated from a full carat. That slight difference in carat weight can save on your engagement ring without her (or her friends) knowing the difference.
Stay clear of princess cuts when looking for an engagement ring. This cut requires a higher carat weight, not to mention the fact that princess cut diamonds tend to look smaller by comparison. To get the most bang for your buck, and to save on her engagement ring, look towards round and marquis cut diamonds.
The single stand alone solitaire was still available but not the only choice anymore, although it is still considered one of the best quality engagement rings. With the introduction of wider bands to incorporate baguette diamonds, accenting the solitaire has started to become the norm. There are still traditionalists out there and this is perfectly fine. Personally my fiance has a solitaire ring, but added to this is a second ring with accent diamonds that is perfectly shaped just to complement this ring. The solitaire itself is a break from tradition. It is a modified marquise diamond in the shape of a tear drop. I gave this as a symbol for the tears I would shed if she was ever to leave me.