There are crown jewels, and then there are Cartier watches. Sometimes, they are one and the same.

This weekend, Santa Barbara businesswoman Meghan Markle treated admirers to a glimpse inside her California-meets-Kensington jewelry box when she took one of Princess Diana’s timepieces out for a spin at Kevin Costner’s One805Live! charity benefit.

The Duke and Duchess of Sussex, who champion psychological well-being via their Archewell Foundation, took the stage to present the Heart of the Community Award to the County Fire Department’s Peer-to-Peer mental health program.

Joining her husband on stage, Markle wore a new navy blue Carolina Herrera halter dress ($2,490) and accessorized with several pieces of gold jewelry, including her late mother-in-law’s Cartier Tank Française watch.

The 44-year-old “Suits” alum, who purchased a two-toned version of the luxury timepiece for herself in 2015, is fond of sentimental jewelry.

“I had it engraved on the back, ‘To M.M. From M.M.’ and I plan to give it to my daughter one day,” she told Hello! of the splurge. “That’s what makes pieces special, the connection you have to them.”

Notably, Markle’s three-stone engagement ring from Prince Harry, 41, features diamonds from the late Princess Diana’s personal collection.

Markle epitomized the weekend-event version of California cool, pairing her off-the-rack backless dress with tan high heels by Ralph Lauren and a top-handle raffia bag from Hunting Season.

This marked the couple’s first public appearance since Prince Harry’s trip across the pond, where he attempted to reconcile with his father, King Charles III.

It also follows the Season 2 premiere of “With Love, Meghan,” Netflix’s lifestyle and cooking show with the California-born duchess, which received lackluster reviews.