What To Get Mom For Christmas? (tiffany & Co.)?

Hello,
My brother and I want to buy something nice for mom for Christmas. We are going to get her something from Tiffany & Co. We made a list of some of the things she might like, but there are so many to choose from. We went to the website and our location is the US, but we are not going to be ordering online instead we are picking it up. I posted here to and elsewhere hoping that people would add their own ideas. ($100-$500 is our price range)
What are some good ideas to get for mother.