Exes Gwyneth Paltrow and Chris Martin Reunite for Apple's Graduation

Gwyneth Paltrow and Chris Martin had a reunion of sorts this week ... all to celebrate their daughter's college graduation.

Apple got her diploma from Vanderbilt University in Nashville ... after majoring in law, history, and society. Smart (organic, gluten-free, grain-free, vegan) cookie!

The movie star and rocker share two kids ... Apple and her bro, Moses -- and the pair have said over the years they've maintained a friendly relationship since their split in 2014. Still ... it's rare to see them together out in public.

Gwyneth attended the ceremony with hubby Brad Falchuk ... while Chris was snapped chilling with Moses.

Earlier this year, Apple told Vogue ... her initial plans to go to law school had changed ... and she was ready to follow in mom's footsteps, adding ... "I love dancing and I love acting. My dream is to act."