Stone, 26, and Garfield, 31, began dating in 2011, reported Hollywood Life.
They are planning 'a dramatic and memorable' wedding for the summer of 2015 and the actress has apparently decided on the dress.
"Andrew would be happy with a city hall ceremony. But Emma wants something more dramatic and memorable," a close friend of the pair revealed.
The couple are planning to keep the ceremony very intimate and will say their vows in front of 25 friends and family.