Rihanna was reportedly "shocked" by the ballplayer''s surprise, as he had initially planned a very "private and intimate" gathering for her, reports TMZ. "Matt really wanted to do something nice for Rihanna this year since she didn't have much of a 21st birthday last year," the New York Daily News quoted a source as saying. Kemp also reportedly surprised the singer with a custom diamond necklace. The insider said: "It was so sweet and she was really surprised. She looked just beautiful."