Why the Stone Looks Larger
Invisibly set diamonds appear in a seemingly continuous flow, without any interruptions by prongs or bezels. Your first look at it would leave you with the impression of a large diamond, the ring has several smaller ones instead. This lowers the cost considerably, seeing as a smaller stone can always be used for a comparable effect.
Other benefits of this setting include enhanced safety for the gem, and boosted shine as a result of so many diamonds being set so closely together, without a visible setting blocking any of the light they exude.