A double sided indexable cutting insert having a central insert axis extending perpendicular to an insert mid-plane, and comprising: two end surfaces and a peripheral surface extending therebetween, the end surfaces located on opposite sides of the mid-plane, each end surface having three primary apexes and three secondary apexes; and six cutting portions, each formed along the intersection of the peripheral surface and one of the end surfaces, each cutting portion comprising a first cutting edge and a second cutting edge extending transversely to the first cutting edge, a tip cutting edge extending therebetween at one of the primary apexes, and a ramping cutting edge extending between the second cutting edge and the first cutting edge of an adjacent cutting portion; wherein: the peripheral surface has a plurality of clearance surfaces, each extending from one of the second cutting edges in the direction of the mid-plane, each of the first cutting edges has a major portion extending from the respective tip cutting edge towards the mid-plane, and a curved portion extending from the major portion and curving away from the mid-plane, and each end surface has an insert abutment surface on an abutment plane, the abutment planes being parallel to the mid-plane and equidistant therefrom, characterized in that each of the curved portions lies between an adjacent abutment plane and an adjacent primary apex, in a direction parallel to the central insert axis, wherein the peripheral surface has a plurality of side flanks, each extending between a pair of primary apexes located on opposite sides of the mid-plane, and an adjacent pair of secondary apexes located on opposite sides of the mid-plane, and at each primary apex, each pair of side flanks forms a first acute angle (α) therebetween. two end surfaces and a peripheral surface extending therebetween, the end surfaces located on opposite sides of the mid-plane, each end surface having three primary apexes and three secondary apexes; and six cutting portions, each formed along the intersection of the peripheral surface and one of the end surfaces, each cutting portion comprising a first cutting edge and a second cutting edge extending transversely to the first cutting edge, a tip cutting edge extending therebetween at one of the primary apexes, and a ramping cutting edge extending between the second cutting edge and the first cutting edge of an adjacent cutting portion; wherein: the peripheral surface has a plurality of clearance surfaces, each extending from one of the second cutting edges in the direction of the mid-plane, each of the first cutting edges has a major portion extending from the respective tip cutting edge towards the mid-plane, and a curved portion extending from the major portion and curving away from the mid-plane, and each end surface has an insert abutment surface on an abutment plane, the abutment planes being parallel to the mid-plane and equidistant therefrom, the peripheral surface has a plurality of clearance surfaces, each extending from one of the second cutting edges in the direction of the mid-plane, each of the first cutting edges has a major portion extending from the respective tip cutting edge towards the mid-plane, and a curved portion extending from the major portion and curving away from the mid-plane, and each end surface has an insert abutment surface on an abutment plane, the abutment planes being parallel to the mid-plane and equidistant therefrom, characterized in that each of the curved portions lies between an adjacent abutment plane and an adjacent primary apex, in a direction parallel to the central insert axis, wherein the peripheral surface has a plurality of side flanks, each extending between a pair of primary apexes located on opposite sides of the mid-plane, and an adjacent pair of secondary apexes located on opposite sides of the mid-plane, and at each primary apex, each pair of side flanks forms a first acute angle (α) therebetween.