McDonald's just created a $12,500 gold-and-diamond ring that looks like a BIG MAC. And you can win it by tweeting about why you love Big Macs.FULL STORY: I'm not sure I'd want to walk around wearing a giant, gold, diamond-encrusted hamburger on my finger . . . but you might. And now you can.McDonald's just had a jewelry designer make a Big Mac RING. It's made from 18-karat gold . . . it's got a bunch of diamonds, sapphires, and other jewels . . . and it's worth approximately $12,500.And if you want it, all you have to do is tweet about your love of the Big Mac using the hashtag #BlingMacContest before Valentine's Day.