The media personality's birthday is Tuesday -- though she was clearly intent on starting festivities early -- no doubt hoping to ring in her milestone year, which included her engagement and a Vogue spread.
Lauren's been painting the town red, almost literally, sharing an IG snap of herself and pals dolled up in sexy scarlet 'fits.
She expressed gratitude at celebrating her birthday with her girl gang ... saying she considers them family and loves them deeply.
Lauren added she always has a lot of fun with them, which seems clear based on reports of her squad letting their hair down Fri night ... with LS busting out her best dance moves on top of a table.
They add that other notable figures were present ... including movie producer Brian Glazer, media mogul David Geffen, IAC head Barry Diller, MicroStrategy's Michael Saylor -- and Lauren's sister Elena.
During their stay at the Caribbean island, Lauren is hunkering down with Jeff aboard this $500 million superyacht, Koru.
Clearly, Lauren was always destined for the bling life.