Newly-Engaged Jeff Bezos, Lauren Sanchez Head Back to Superyacht in Cannes

Jeff Bezos and Lauren Sanchez are celebrating their engagement on the romantic French Riviera ... and it's not just her giant diamond ring that's turning heads in Cannes.

The Amazon founder and his fiancée Lauren had a dinner date Monday night at La Petite Maison, where the soon-to-be-newlyweds dined with Jeff's sister, Christina, and her hubby Steve Poore. No doubt the family members were toasting Jeff and Lauren's big news.

And yes, Lauren's massive rock on her left hand drew plenty of attention ... along with her stylish white mini-dress!

As we reported, Lauren's engagement bling was first spotted while she and Jeff were aboard his new $500 mil superyacht, Koru. The couple sailed out of Mallorca, Spain, and beelined it for all the festivities around the Cannes Film Festival.

Lauren and Jeff started dating in late 2018, and they've been inseparable since ... traveling around the world together.

Unclear when Jeff and Lauren are going into wedding-planning mode, if they aren't in that zone already ... but odds are it'll be an extravagant affair. Comes with being one of the world's richest!!!

We covered it all in the latest episode of The TMZ Podcast, available on all podcast platforms.