Alexis Bledel Debuts Octagonal-Cut Diamond Engagement Ring

That's some sparkler!

Alexis Bledel debuted her engagement ring on the red carpet Wednesday. The actress, perhaps best known for her roles on "Gilmore Girls" and in the "Sisterhood of the Traveling Pants," was at the Los Angeles premiere of her new TV movie, “Remembering Sunday."

Outfitted in a basic colored black-and-ivory dress with sexy cutouts, the 31-year-old let her new accessory -- given to her by fiancé Vincent Kartheiser, 33 -- have its big moment in the spotlight.

[Related: Alexis Bledel, Vincent Kartheiser Engaged! 'Mad Men' Costars to Marry]

And what a ring! The large, octagonal-cut diamond is set on what appears to be a platinum band. The unusual cut sets it apart from other engagement rings we've seen on Hollywood stars.

Bledel, who had meticulously manicured digits for her ring's big debut, posed with her hand on her hip, giving photographers the perfect shot.

The actress met Kartheiser on the set of "Mad Men" last year during her guest-starring role as his character Pete Campbell's neighbor -- and mistress -- Beth Dawes. The couple made their red carpet debut in October and announced their engagement in March.

[Related: ‘Mad Men’ Lovebirds Vincent Kartheiser and Alexis Bledel Step Out as a Couple]

As far as wedding planning goes, Bledel has said it will be a joint production.

"We're doing it together," she told Us Weekly, though admitted, "We haven't started yet though."

She'll have plenty of time for that. For now, she can just enjoy her new bling.

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