Someone wants to make darn sure the world knows Ryan Reynolds' fist wasn't as tight as his abs when it came to decorating the fourth digit of fiancée Scarlett Johansson's left hand.

A snitch helpfully informs TMZ.com that the sparkling solitaire the starlet has been showing off is bigger and pricier than initial reports suggest.

Seems contrary to chatter that the bauble is a measly 3 carats and came with a chump-change $30,000 price tag, it's actually more than four carats and cost the actor $120,000.

Scarlett flashes her carats at the Costume Institute Gala on May 5.

Yes, we, too, are relieved Johansson, 23, has received a diamond as impressive as her décolletage, because big, expensive rocks always guarantee long, happy marriages, especially for squeezes given to public squabbles.

Right?

Meanwhile, did ScarJo's betrothal cause a hitch in her planned appearance at the Cannes Film Festival to promote her latest Woody Allen flick, "Vicky Cristina Barcelona," which received a warm reception from critics?

An insider tells the Los Angeles Times there's no truth to rumblings that Scarlett's so-called "diva demands" over her hair, makeup and hotel resulted in the studio scrubbing the trip.

Instead, the hammered-out arrangements purportedly fell apart when Johansson revealed her altar-bound status on May 5.

"Within 24 hours of the announcement of her engagement, the studio reneged on the agreed-on terms for Scarlett's appearance at Cannes," the source tells the paper. "It was insane. She was backed up against a wall. Finally, she personally made the decision not to go."

But was the about-face sparked by the filmmaker, who has said of his current favorite leading lady, "She is unlike anyone who has come before her, and while she is a much stronger actress in every way, there is a tiny bit of Marilyn Monroe in her zaftig humidity."

When asked if there was a chance Woody was "annoyed" by Scarlett's engagement, the mole responded, "Yes."

As for the studio, it blames "scheduling conflicts" for her absence and decries the diva 'tude rumors as false, pooh-poohing to the paper, "These reports circling about Scarlett are simply untrue and unfair."

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