Almond Crust Preparation: In a bowl, mix cookies crumbs, almonds, sugar and butter. Press uniformly the mixture in the bottom and sides of a 9 inch spring form pan, until 1 inch high. Set aside in the fridge.
Preparation of garnish: In a big bowl, with a mixer, beat cream cheese and 1 cup sugar until homogeneous. Add eggs, one at a time, beating well between each egg. Add juice and peel of grapefruit and mix well.
Pour cheese mixture in the reserve crust and cook in a preheated oven of 350 F, 50 to 55 minutes or until the sides is set (shake delicately the pan to check if it's set) Let cool in the oven that is now at off, with the door half-open, to avoid that the top of the cake splits.
Mix sour cream and remaining sugar. Spread on the cold cheesecake. Arrange the grapefruits' supremes in concentric cercles on the sour cream mixture.