Karina Smirnoff giant engagement ring

Karina Smirnoff shows off her giant diamond engagement ring. Photo: Denise Truscello, WireImage

"Dancing With the Stars" pro Karina Smirnoff may be light on her feet, but her ring finger just got a whole lot heavier.

The 32-year-old Ukrainian beauty flashed a 4.5-carat, princess-cut diamond at a Tao Las Vegas party this weekend and fessed up that she's been secretly engaged to her professional baseball-player beau, Brad Penny, since Oct. 13.

Penny popped the question in Malibu, Calif., while Smirnoff was still competing with "DWTS" partner, Mike "The Situation" Sorrentino. The ab fab pair has since been eliminated.

Formerly engaged to fellow "DWTS" pro Maksim Chmerkovskiy, the dancer told People her manager summoned her to a ruse business meeting at a seaside restaurant, then excused herself, and that's when Penny arrived to propose on bended knee.

Penny gave the ballroom diva a bauble that could even outshine the show's tacky but coveted mirror-ball trophy: The sparkler features a center-cut stone set on a platinum band that includes smaller, channel-set, princess-cut diamonds, according to Us Weekly.

Jewelry expert Michael O'Connor tells the mag he estimates the price tag at $95,000 and pronounced it a ring fit for a "fairy-tale princess."

At Tao's fifth anniversary party, Smirnoff seemed happy to flash her bejeweled finger.

"My family is from New York and Brad's is from Oklahoma so we kind of wanted to come out and celebrate and be a family first before we let the cat out of the bag," Smirnoff told People.

"Thank you all so much for ur warm wishes," she tweeted Nov. 7. "I feel very lucky and blessed...Yayayay!"

Smirnoff is just the latest reality celeb to receive big bling from her chosen one. Read about the Asscher-cut Neil Lane ring former "Bachelorette" Ali Fedotowsky was given by fiancé Roberto Martinez.

And StyleList also has the scoop on the Asscher-cut whopper singer Nick Lachey gave "True Beauty" host Vanessa Minnillo for their recent pre-birthday proposal.

In other "DWTS" news, read what the show's Emmy-winning costume designer, Randall Christensen, had to say about letting The Situation bare his famous abs.