1.Preheat oven to 180°C (160°C fan-forced).
2.Cut through rind about 10cm from shank end of leg; run thumb around edge of rind just under skin to remove rind. Start pulling rind from widest edge of ham, continue to pull carefully away from fat up to the cut; remove rind. (Reserved rind can be used to cover the cut surface of ham to keep it moist during storage.)
3.Using sharp knife, score fat by making shallow cuts diagonally in both directions at 3cm intervals.
4.To make blood orange marmalade glaze, stir marmalade, sugar and juice in small saucepan over low heat until sugar is dissolved.
5.Line a large baking dish with overlapping sheets of baking paper. Place ham on wire rack in baking dish; brush well with glaze. Cover shank end with foil.
6.Roast, uncovered, 40 minutes. Push a clove in centre of each diamond shape; roast further 40 minutes or until browned all over, brushing occasionally with glaze during cooking.
7.Serve ham slices warm or cold.