Warning: If the season finale of Entourage is waiting on your TiVO and you haven’t watched it yet, come back and read this post later as it contains spoilers.

On the season finale of HBO’s Entourage, Matt Damon stole the show with a guest appearance as a well-meaning yet overbearing version of himself. But another dazzling cameo slipped under the radar.

Damon pressures Vincent Chase (Adrian Grenier) to contribute time and money to OneXOne, a charity for which Damon is a real-life ambassador. Damon won’t take no for an answer, enlisting Bono and LeBron James to help pressure the vacuous Vince while frequently growling, “It’s for the kids.” At one point, Vince tries to have his brother Johnny “Drama” (Kevin Dillon) screen a phone call from Damon. After only a few seconds of talking to a determined Damon, a flustered Drama hands the phone to Vince anyway, apologetically saying, “He Jason Bourne’d me.”

The storyline is all the more amusing in light of Grenier’s actual personal commitment to good causes. Grist’s Claire Thompson recently named him part of Hollywood’s next green generation, citing among other things Grenier’s 2008 Blue Sky Award for Environmental Activism at the Vail Film Festival. (Side note: Why is it always the female Gristers who write about Grenier? Weird.)

Grist thanks its sponsors. Become one.

But the other message of social responsibility came during a separate storyline — and it was both surprising and subtle. Eric “E” Murphy (Kevin Connolly) unexpectedly proposes to his ex-girlfriend, Sloan, at a pivotal moment, pulling a ring box out of his pocket.

Brilliant Earth on Entourage

Grist thanks its sponsors. Become one.

That’s a Brilliant Earth ring!” my fiancee exclaimed. I recently gave her a Brilliant Earth ring of her own and she immediately recognized the distinctive sustainable wood ring box. (Since we’ve already covered the spoiler alert, Sloan accepts the ring.)

I called Brilliant Earth and began, “So I was watching Entourage last night …”

“Yup, it was one of ours,” the voice on the other end immediately laughed. She said only a few people had caught the quick appearance.

A Brilliant Earth spokeswoman emailed me some more details:

HBO’s Entourage reached out to Brilliant Earth a few months ago, and requested to shoot our rings and boxes for their finale episode of season 6. Someone senior on the show is a Brilliant Earth customer and asked the props department to only source the rings from Brilliant Earth. Of course, we were thrilled to be involved in the show — we are huge fans! Entourage selected our Recycled Platinum Four Prong Classic Ring set with a 2 carat round brilliant center diamond for E’s proposal to Sloan. They showed the ring in one of our signature hand-crafted, sustainably harvested Rimu wood ring boxes.

Entourage has been a large promotional platform for a variety of brands and we are very proud that they chose to promote Brilliant Earth’s social mission to provide conflict-free diamonds and recycled gold & platinum. We were particularly impressed that they did not ask for any compensation for the feature despite the broad audience exposure. It’s very inspiring for us to see our ethical mission in the spotlight on Entourage and applaud their efforts to raise awareness of social issues and ways for their audience to effect positive change.

Congrats to the producers of Entourage for delivering the best charitable and green messaging possible — casual, subtle, and best of all, fun.

Full disclosure: I’ve seen Brilliant Earth ads on Grist, but I’m a guest contributor and that doesn’t influence my posting. Definitely no discount on my ring. Was that an actual disclosure? Not really, I guess, but wanted to put it out there.

Photo courtesy HBO & Brilliant Earth