Get more info here: Henri Bendel Fall 2012 Open See.
There can often be tons of people waiting to be seen, so go as early as you can and be prepared to wait. I brought my handmade jewelry many years ago to an Open See they had in Los Angeles, and while the rejection was swift, it was still a very interesting and educational experience. I brought jewelry samples in a shoebox (literally!) and probably should have prepared just a little bit more.
You can start by checking out the other lines carried at Henri Bendel and decide if your work fits in. Henri Bendel has been a New York institution for many years and it is known for accessories (think scarves, gloves and hair accessories). It's like your fashionable Aunt's closet. Think beautiful details and luxe finishes, but at a wide range of price points.
Bring samples of your work that really speak to what you are about, your very best and most representative pieces. Have your story ready for the buyer (that you can give in 30 seconds or less), and know what your target market and price point is. They want to know what your design aesthetic is (like they say on Project Runway -- what does your jewelry say about you?) and how they would market you next to the other designers they already carry.
Even if the answer is "no", remember to be gracious and polite, and be sure to get contact info and request if it would be OK to follow up (and go off and refine your pitch!). I got a the business card of the jewelry buyer before leaving.