1. Divide pear juice among 4 small bowls. Add 2 drops of food coloring and 1 drop of vanilla to each bowl. Place a pear half in each bowl. Cover with plastic wrap, and refrigerate 30 to 40 minutes.
2. To serve, slice pear halves crosswise into wedges and arrange in a pinwheel shape. Place a cranberry in center. Repeat to make second pinwheel.