The party never stops!

Before she whooped it up with pals at Las Vegas' PURE Nightclub on Saturday, Ashley Greene's birthday weekend kicked off with a low-key dinner at STK in West Hollywood on Friday.

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Organized by her beau Joe Jonas, a source tells that the Disney star visited Greene's "favorite restaurant" earlier in the afternoon to oversee every last detail -- including arranging for a scrapbook and a bouquet of flowers to be on display when they arrived together later that evening.

"This is her first birthday they've spent as a couple, so he wanted to make sure everything was perfect," the insider says. "He was really sweet and conscientious, making sure everything worked out okay."

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Dressed in a lacy black mini, Greene and Jonas, 21, joined 15 of the actress' closest friends -- including her Twilight costar Kellan Lutz -- for a champagne toast.

"Joe had his arm around Ashley the whole night," an eyewitness tells Us.

Though the party ended just before midnight, Jonas' sweet surprises were far from over: he later gifted Greene with a vintage Chanel bracelet, which she wore to the Vegas fete the following night.

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"The funny thing about it is when I got it, my boyfriend said it was vintage Coach," Greene told reporters. "It was very cute and sweet and adorable to me because my boyfriend gave it to me. Coach, Chanel -- it makes no difference to him, but to me this is amazing. I thought it was adorable and I absolutely love it because he knows what I like."

"Thank you to all my incredible friends family and fans for the sweet birthday wishes," Greene tweeted early Sunday morning. "I'm a very lucky girl to have you all in my life."

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