First observation: It’s true that the pit prevents guacamole from browning, but only the part directly under the pit. In fact, there’s no magic to it; the pit simply blocks contact with the air. It’s not very effective, given that the rest of the guacamole will brown anyway.
To keep your guacamole from browning, simply add some lime juice (which is a traditional ingredient in Mexican guacamole) because it contains ascorbic acid, an antioxidant compound that prevents browning. The surface can also be protected by covering it with plastic film and pressing it directly onto the guacamole.
To find out more on how to cut and enjoy your avocado, be sure to read this article: