Here is a 5.97 carat ametrine which measures 10.4 mm. across. In an experiment to see if the two colors would show rather than mix, I tried using concave facets on two sides of the pavilion to make it really bright, and using steep angles on the other two sides (similar to a method used for closed C axis tourmalines.)
It seemed to work somewhat. As usual, the camera showed the difference more than it seemed to me. And also added a bit an impressionist painting look to the stone.