NEW PALS: The massive Christmas tree wasn’t the only thing on display at Rockefeller Center on Tuesday afternoon. Just a few feet away, Ivanka Trump and Brian Reyes were showing off of their respective spring collections to the likes of Celerie Kemble, Marjorie Gubelmann and Olivia Chantecaille at Christie’s. The event was the duo’s first collaboration. “We just met, like, six minutes ago,” said Reyes of his co-host, who donned a dress from his pre-spring line for the occasion. “I was rockin’ this at the office earlier,” said Trump, who paired the diaphanous frock with an even less office-appropriate accessory — a 6.5 carat pink diamond necklace from her jewelry line.