1. Finely grate 1 teaspoon each of grapefruit zest, orange zest and clementine zest into a large bowl and add the sugar.
2. Using a sharp knife, peel the citrus, removing all of the bitter white pith. Working over the bowl, cut the grapefruits and oranges in between the membranes and release the sections into the bowl. Squeeze the juice from the membranes over the fruit. Cut each clementine into eighths. Add to the bowl along with the sugar and ginger and stir. Sprinkle with the almonds just before serving.