Sorry boys, It appears as if Scarlett Johansson really is taken. As we noted yesterday, 2006's Sexiest Woman Alive got engaged to equally easy-on-the-eyes boyfriend Ryan Reynolds, and judging from ScarJo's behaviour last night at the Costume Institute Gala, the soon-to-be-bride appears incapable of hiding her joy. All smiles as she walked the carpet, Johansson even did the paparazzi a favour by flashing her new rock, and her choice to wear an off-white demure dress helped us paint some mental images of her upcoming walk down the aisle. But how does her ring compare to infamous engagement rings of the past (J. Lo's sad pink diamond monster mid-Bennifer trainwreck) and rings recently sported by newly engaged stars like Mariah Carey and Ashlee Simpson? We compare and contrast after the jump.

Though it's too early to tell how many carats Scarlett's rock has, we have read that Reynolds bought his former fiance, Alanis Morissette, a 3.75 carat rock.

Naturally, Katherine Heigl had her 3 carat ring designed herself rather than trusting her frequently emasculated husband Joshua Kelley pipe in with any kind of opinion. Mariah Carey's highly confusing recent engagement to Nick Cannon has resulted in the singer sporting a possibly recycled 15 (yikes!) pink and purple tacky thing, but if anyone can pull of giant gems it would be Mimi. And, of course, Jennifer Lopez, whose infamous $1.2 million pink diamond ring was ostentatiously flashed 'round the world, only to be sold off post-breakup.

While poor Carmen Electra's new rock from rocker Rob Patterson cost a mere $100k (for celebs, that's the equivalent of shopping at Jared), we think Patterson's eccentric choice of a black diamond suits Electra perfectly. As for knocked up Ashlee Simpson, her faux-punk rocker fiance Pete Wentz reportedly made sure to give Simpson a ring without those pesky "blood diamonds" Leonardo DiCaprio taught us all about in that boring movie of the same name.

[Photo credits: Wireimage, The Mirror]

• DEFAMER WEDDINGS: SCARLETT JOHANSSON AND RYAN REYNOLDS ENGAGED TO EACH OTHER [Defamer]

Tags: ashlee simpson | ben affleck | defamer weddings | jennifer lopez | josh kelley | katherine heigl | mariah carey | nick cannon | pete wentz | rocks of love | ryan reynolds | scarlett johansson | the emasculation of joshua | wireimage