The potatoes are done when the caramelized sugar bubbles and browns around the sides of the pan.
In a large saute pan over medium-high heat, melt butter. Add potato wedges to the pan, and stir until coated with butter. Add 1 cup water and the orange juice; cover, and cook until potatoes are fork-tender, about 5 minutes.
Remove cover, reduce heat to medium, and continue cooking, tossing occasionally, until most of the liquid has evaporated, 3 to 4 minutes more.
Combine sugars, and sprinkle over potatoes; toss until coated. Continue cooking until the sugar starts to caramelize and potatoes have a brown glaze, 5 to 6 minutes, tossing occasionally to prevent potatoes from burning. When caramelized sugar bubbles and browns around the edges, remove potatoes from pan. Season with salt and pepper, garnish with orange zest, and serve immediately.