Cristiano Ronaldo and Georgina Rodríguez Are Engaged. All Eyes Are on the Ring.

In an Instagram post on Monday, Georgina Rodríguez, the longtime girlfriend of the soccer superstar Cristiano Ronaldo, shared a photo of a gigantic rock on her ring finger. Beneath her hand, adorned with long, freshly manicured, glazed French nails, was another person’s hand — presumably Mr. Ronaldo’s, since he was tagged in the photo.

“Yes, I do. In this and in all my lives,” she captioned the photo in her native Spanish.

Immediately, the oval-cut ring had people talking. Some people compared the diamond ring to a Ring Pop, the lollipop candy, and others joked that it was probably so expensive that it could save world hunger.

“To wear this stone regularly, you’re going to need a finger reconstruction surgery,” Julia Chafé, a jewelry-focused social media influencer, said in a video on Instagram. “Just imagine wearing a hundred-pound kettlebell on your finger all day, every day. Painful, but worth it.”

Anya Walsh, a jewelry specialist at 77 Diamonds, a retailer based in London, said she was surprised to see a diamond ring that large.

“Usually when you see even celebrity proposals, it’s around two to three carats or maybe five carats,” Ms. Walsh said. “This ring is in a league of its own. It’s taking a good third of her finger, size-wise.”

But it did remind her of a few other rings worn by celebrities and socialites.

Ms. Walsh estimated the cost of Ms. Rodríguez’s ring to be at least $5 million, and the total weight to be around 35 carats. She said it looked similar to Mariah Carey’s 35-carat emerald-cut engagement ring in 2016 from her billionaire ex-fiancé, James Packer.

The ring also reminded Ms. Walsh of Elizabeth Taylor’s 33-carat stone, gifted by her ex Richard Burton in 1968. It sold for $8.8 million at a Christie’s auction in 2011.

Mr. Ronaldo, the most followed person on Instagram, with over 660 million followers, and a man with a level of international fame that cannot really be overstated, is bound to inspire trends with his engagement ring.

“This is one of the biggest celebrity engagements we’ve seen in a while,” Ms. Walsh said. “So many people are really huge fans of him. A lot of men as well. I can guess there’s going to be an uptick in oval diamonds for sure, but will people want larger diamonds now?”

Oval diamonds are popular for their romantic, soft look. “Even though this is a huge diamond, it has that sort of contour where it’s quite delicate,” Ms. Walsh said. After the round brilliant ring, the oval diamond is the second most popular choice at 77 Diamonds, generating about 20 percent of total sales.

“Because it’s an elongated diamond, it helps also make your hand seem a bit more slender, a bit finer than a more geometric or rectangular-looking stone,” Ms. Walsh added.

Ms. Rodríguez’s engagement ring also appears to be flanked by two smaller oval diamond side stones, which is called a trilogy design. The three diamonds typically signify the past, present and future.

Olivia Landau, the founder of the Clear Cut, a jeweler in New York, said the side stones appeared to be around three carats each. She predicted that the three-stone ring, with three ovals, would be more popular now, though on a smaller scale.

Ms. Landau also said that, given Ms. Rodríguez’s track record with fine and high jewelry, she believed it was a natural diamond. “She’s known for being a maximalist with her jewelry,” Ms. Landau said.

Ann Grimmett, the vice president for merchandising at Jared Jewelers, estimated that the diamond was 30 to 40 carats, costing anywhere from $5 million to $15 million.

And George Khalife, a celebrity jeweler known as George the Jeweler, estimated that it was around 20 to 25 carats, and around at least $5 million to $7 million. “Knowing that it’s Cristiano Ronaldo, I’m assuming it’s probably near colorless (F color), likely a VVS quality,” Mr. Khalife said, noting that the diamond appeared to be nearly flawless.

“Knowing who he is and knowing his impact on the world and his popularity,” Ms. Walsh said about Mr. Ronaldo, “I don’t think he could have done it any other way.”