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Joel Madden is smart enough to know when to get the heck out of Nicole Richie's way. People magazine says he took a backseat when it came time for his newly minted fiancée to select her engagement ring.

The mom of 2-year-old daughter Harlow and 5-month-old son Sparrow created her sublime, supersized handmade sparkler with jeweler-to-the-stars Neil Lane, spending a month weighing her bauble choices before deciding on a four-plus-carat round diamond.

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The honker of a rock is surrounded by an octagonal diamond frame and set off with a platinum and diamond band (we're sensing a "precious stones, yay!" theme here).

"Nicole wanted a beautiful, special ring, and wanted to be intimately involved in the design," Lane tells the mag of collaborating with the part-time jewelry designer. "Nicole was lovely and wonderful to work with on it! We designed it together."

Madden, adds the jeweler, "just wanted her to have her dream ring."

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The rock was ready just in time for Richie to break the engagement news during her sit-down with David Letterman on Monday (the interview airs Friday).

As for the actual knot-tying, PopEater believes they're planning to say "I do" this summer during an intimate, low-key affair.

"Nicole wants to keep the ceremony to close friends and family," relays an insider. "It will be traditional with a simple white dress and very private."

The couple's tots are expected to participate in the vow-swap, and Lionel Richie has already gushed to People about how excited he is to walk his little girl down the aisle.

But one face that apparently won't be front-and-center at the wedding is Nicole's former reality show partner-turned-frenemy-turned-sometime friend, Paris Hilton.

She "will not be a bridesmaid," insists the source.

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Meanwhile, in a now-deleted tweet by Madden, he reveals that he and Richie have been engaged "for a while" but shared the good news only with their evidently discreet inner circle.

"P.S. That's why I love my family and friends," wrote the Good Charlotte front man. "None of them are sources. All good tight-lipped people who let us enjoy it! Thanks, everybody."

Nicole and Joel began dating in late 2006, and over the course of their relationship, she has transformed from a scrawny, DUI-busted cautionary tale to a doting mom, fashion designer and do-gooder.

During her chat with Letterman, she readily agreed when he pointed out how "everything changes" when you have kids.

"It sounds cheesy to say, but it does," Richie said. "Your whole life changes and your priorities change 100 percent ... in the best way possible."

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