Christina Haack Shows Off Her Massive Emerald-Cut Diamond Engagement Ring from Fiancé Joshua Hall

Just hours after announcing her engagement to boyfriend Joshua Hall on Monday, Christina Haack showed off her new massive ring on her Instagram Story.

The Christina on the Coast star, 38, thanked Benny Hayoun of Los Angeles-based Benny and the Gems for designing the emerald-cut sparkler, which sits on a band covered in pavé diamonds. "Thank you @bennyandthegems - great friend and best jeweler," Haack captioned the post.

To announce her engagement to Hall, Haack shared three photos of her and the Austin-based realtor enjoying a sunset dinner in Los Cabos, Mexico, where they're currently celebrating his birthday, with a diamond ring featured in two of the photos. The pair are sharing a kiss in the third.

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Haack captioned the post with five emojis: A heart, an infinity sign, a lock, a key and a ring. Fans took to the comments section to send their congratulations.

The HGTV star and mom of three also changed her Instagram bio to read: "Mommy. 💍 Josh Hall."

One day earlier, Haack shared a photo of her and Hall at the beach in honor of his birthday, alongside some heartfelt words for her beau.

"Happy birthday baby. You give me that teenage kinda love vibe and manly protection," she captioned the image. "It's a combo for a lifetime of happiness + success."

"Thank you for reminding me what life and love are like when you put down the technology," Haack added. "I love you Josh."

The engagement news comes two months after PEOPLE exclusively confirmed in early July that Haack was in a new relationship, as she and Hall celebrated her 38th birthday with a getaway to Mexico.

Haack later revealed that she and Hall had been dating for months, writing in an Instagram post, "When we met this past spring, the synchronicities hit us so hard and fast they were impossible to ignore."

Her marriage to Hall will be the third for Haack. She was previously married to her Flip or Flop costar Tarek El Moussa from 2009 to 2018 and Celebrity IOU: Joyride host Ant Anstead from 2018 to 2021.

Last year, El Moussa proposed to his now-fiancée Heather Rae Young with an eight-carat, colorless, emerald-cut diamond engagement ring, also designed the same jeweler Hall chose, Hayoun of Benny and the Gems.

"The diamond is perfect all the way around, just like Heather," El Moussa told PEOPLE about his selection at the time. "I also picked this ring because eight is a lucky number."

On Monday morning, Hayoun posted an Instagram photo of Young flashing her engagement ring during on Sunday's episode of Celebrity Family Feud with the caption, "Only one ring can blind the bling empire and leave them speechless."

Haack shares daughter Taylor Reese, 10, and son Brayden James, 6, with El Moussa, and son Hudson London, 2, with Anstead.