An indexable cutting insert comprising two opposing end surfaces with a peripheral side surface and a central axis extending therebetween, the cutting insert having four cutting portions (26a, 26b, 26c, 26d), four spaced apart abutment zones (28a, 28b, 28c, 28d), and mirror symmetry about mutually perpendicular first and second planes (P1, P2) containing the central axis, each of the four cutting portions (26a, 26b, 26c, 26d) having a cutting edge (32a, 32b, 32c, 32d) formed by the intersection of a rake surface (34a, 34b, 34c, 34d) and a relief surface (36a, 36b, 36c, 36d), the four rake surfaces (34a, 34b, 34c, 34d) and the four relief surfaces (36a, 36b, 36c, 36d) located on the peripheral side surface; and each of the four abutment zones (28a, 28b, 28c, 28d) representing a distinct region of the peripheral side surface capable of making clamping contact with a corresponding region of a mating component in at least one index position of the cutting insert, wherein: the peripheral side surface includes two pairs of opposing side surfaces (38a, 38b), a first pair of opposing side surfaces mirror symmetrical about the first plane, and a second pair of opposing side surfaces mirror symmetrical about the second plane, the four cutting edges (32a, 32b, 32c, 32d) are formed at the intersections between the two pairs of opposing side surfaces (38a, 38b), the second pair of opposing side surfaces includes the four rake surfaces (34a, 34b, 34c, 34d) and the four abutment zones (28a, 28b, 28c, 28d), and characterised in that each of the four abutment zones is planar and in that each of the four planar abutment zones (28a, 28b, 28c, 28d) forms an external abutment angle (α1) of less than 180° with another one of the four planar abutment zones (28d, 28c, 28b, 28a). each of the four cutting portions (26a, 26b, 26c, 26d) having a cutting edge (32a, 32b, 32c, 32d) formed by the intersection of a rake surface (34a, 34b, 34c, 34d) and a relief surface (36a, 36b, 36c, 36d), the four rake surfaces (34a, 34b, 34c, 34d) and the four relief surfaces (36a, 36b, 36c, 36d) located on the peripheral side surface; and each of the four abutment zones (28a, 28b, 28c, 28d) representing a distinct region of the peripheral side surface capable of making clamping contact with a corresponding region of a mating component in at least one index position of the cutting insert, wherein: the peripheral side surface includes two pairs of opposing side surfaces (38a, 38b), a first pair of opposing side surfaces mirror symmetrical about the first plane, and a second pair of opposing side surfaces mirror symmetrical about the second plane, the four cutting edges (32a, 32b, 32c, 32d) are formed at the intersections between the two pairs of opposing side surfaces (38a, 38b), the second pair of opposing side surfaces includes the four rake surfaces (34a, 34b, 34c, 34d) and the four abutment zones (28a, 28b, 28c, 28d), and characterised in that each of the four abutment zones is planar and in that each of the four planar abutment zones (28a, 28b, 28c, 28d) forms an external abutment angle (α1) of less than 180° with another one of the four planar abutment zones (28d, 28c, 28b, 28a). the peripheral side surface includes two pairs of opposing side surfaces (38a, 38b), a first pair of opposing side surfaces mirror symmetrical about the first plane, and a second pair of opposing side surfaces mirror symmetrical about the second plane, the four cutting edges (32a, 32b, 32c, 32d) are formed at the intersections between the two pairs of opposing side surfaces (38a, 38b), the second pair of opposing side surfaces includes the four rake surfaces (34a, 34b, 34c, 34d) and the four abutment zones (28a, 28b, 28c, 28d), and characterised in that each of the four abutment zones is planar and in that each of the four planar abutment zones (28a, 28b, 28c, 28d) forms an external abutment angle (α1) of less than 180° with another one of the four planar abutment zones (28d, 28c, 28b, 28a).