Gossip certainly ranks up there as one of those highly tantalizing yet ultimately hazardous human predilections, like eating too much double chocolate fudge cake. You most definitely aren't alone in your gossip fatigue and frustration, as a recent Randstad survey of more than 1,500 employees found that three out of five workers viewed gossip as their top workplace pet peeve.
And while so many people express dismay at this pernicious phenomenon, most are unlikely to complain about it for similar reasons to you: because they're worried about the impact their protestations would have on their workplace relationships and environment. But a little bit of tension may be worth the price of increased productivity and peace of mind.
To proceed in the most prudent way, I would advise you to be as non-confrontational as possible and to refrain from making accusations or "you" statements, such as, "You are an insufferable chatterbox" or, " I think you must really want to get me fired," a surefire way to taint the workplace waters. The next time she comes up to you and wants to start dishing, you need to say some version of, "I would love to sit and chat, but I have a ton of work that I need to get back to." Each time she comes at you, you need to repeat some version of this refrain. Say it nicely, but say it clearly and consistently.
She wants to dish about some goings on between your boss and that crazy chick from HR? You say, "Hey, that sounds really interesting, but I have to get back to work right now. I need to make an important phone call." She wants to share some tidbits about Donna from down the hall? You say, "Gee, that sounds fascinating, but I have a pressing deadline I must meet so I need to get back to work." You can be infinitely creative with this refrain, but you just need to use it again and again and again...
Eventually, she'll get the point, and will find some other victim to target, perhaps someone who will be more willing than you, human nature being what it is...
Heather Boerner, article in Money-Making-Machines.blogspot.com