Zest blood orange, cara cara orange, and navel orange into small bowl. Measure 2 tablespoons zest; set aside. Peel oranges and slice into 1/2 in. slices. Begin arranging oranges in a single layer on top of sugar mixture, leaving as little space as possible between them. Slices may be cut into half moons or triangles to fill any spaces between the circles. When finished, pat oranges dry with paper towel to absorb any excess liquid.