The center stone constitutes the most expensive part of a classic solitaire ring, accounting for as much as 85 percent of its price. One way to cut down on the cost is to buy a diamond online. At a resource like bluenile.com or diamonds.com, it's possible to save up to 40 percent over prices at brick-and-mortar jewelry stores. Feeling nervous? Both e-tailers offer certified gem reports, as well as a full refund within 30 days on undamaged stones.

Three views of a .11-carat ideal-cut round diamond, Blue Nile, $10,131; 800-242-228 or bluenile.com.