A large center stone can ratchet up the cost of a ring. Levine suggests trimming costs by using a smaller center stone with a setting that increases its visual impact. A "halo" setting, for example, is one where the center stone is encircled with diamonds, adding sparks and flare. "Halos always make the center stone look bigger," says Levine.
Avoiding conventional shapes can also reduce costs. Traditional round brilliant diamonds usually cost more because they require high cutting skill, says American Gem Society's Batson. She recommends opting for a less-expensive shape, such as a square-shaped diamond. "(They) retain a lot of sparkle, which not only helps make a diamond look larger but more beautiful."