A generally rhombus-shaped indexable cutting insert (30, 30') comprising: opposing upper and lower surfaces (36, 38) and a peripheral side surface extending therebetween, the peripheral side surface having alternating obtuse and acute corner surfaces (42, 44) separated by four relief surfaces; a central axis passing through the upper and lower surfaces (36, 38), about which central axis the cutting insert (30, 30') is indexable; a minor vertical plane containing the central axis and intersecting the two obtuse corner surfaces; and a nose cutting edge formed at the intersection of at least one of the upper and lower surfaces (36, 38) with each of the two acute corner surfaces, at least one of the upper and lower surfaces (36, 38) comprising: an engagement surface comprising a single primary engagement element and secondary engagement elements, the primary engagement element having an elongated pair of primary engagement flank surfaces and a primary engagement plane, the primary engagement element exhibiting mirror symmetry about the primary engagement plane, each secondary engagement element including a secondary engagement portion, the secondary engagement portion having an elongated pair of secondary engagement flank surfaces and a secondary engagement plane, the secondary engagement portion exhibiting mirror symmetry about the secondary engagement plane, wherein the primary engagement plane contains the central axis and intersects each nose cutting edge, and wherein each secondary engagement plane does not contain the central axis and wherein the primary engagement element is V-shaped when viewed in a cross-section perpendicular to the primary engagement plane, and each secondary engagement element is V-shaped when viewed in a cross-section perpendicular to its respective secondary engagement plane, characterised in that, the insert has four secondary engagement elements and each secondary engagement plane forms an acute engagement angle (α) with the primary engagement plane. opposing upper and lower surfaces (36, 38) and a peripheral side surface extending therebetween, the peripheral side surface having alternating obtuse and acute corner surfaces (42, 44) separated by four relief surfaces; a central axis passing through the upper and lower surfaces (36, 38), about which central axis the cutting insert (30, 30') is indexable; a minor vertical plane containing the central axis and intersecting the two obtuse corner surfaces; and a nose cutting edge formed at the intersection of at least one of the upper and lower surfaces (36, 38) with each of the two acute corner surfaces, at least one of the upper and lower surfaces (36, 38) comprising: an engagement surface comprising a single primary engagement element and secondary engagement elements, the primary engagement element having an elongated pair of primary engagement flank surfaces and a primary engagement plane, the primary engagement element exhibiting mirror symmetry about the primary engagement plane, each secondary engagement element including a secondary engagement portion, the secondary engagement portion having an elongated pair of secondary engagement flank surfaces and a secondary engagement plane, the secondary engagement portion exhibiting mirror symmetry about the secondary engagement plane, wherein the primary engagement plane contains the central axis and intersects each nose cutting edge, and wherein each secondary engagement plane does not contain the central axis and wherein the primary engagement element is V-shaped when viewed in a cross-section perpendicular to the primary engagement plane, and each secondary engagement element is V-shaped when viewed in a cross-section perpendicular to its respective secondary engagement plane, an engagement surface comprising a single primary engagement element and secondary engagement elements, the primary engagement element having an elongated pair of primary engagement flank surfaces and a primary engagement plane, the primary engagement element exhibiting mirror symmetry about the primary engagement plane, each secondary engagement element including a secondary engagement portion, the secondary engagement portion having an elongated pair of secondary engagement flank surfaces and a secondary engagement plane, the secondary engagement portion exhibiting mirror symmetry about the secondary engagement plane, wherein the primary engagement plane contains the central axis and intersects each nose cutting edge, and wherein each secondary engagement plane does not contain the central axis and wherein the primary engagement element is V-shaped when viewed in a cross-section perpendicular to the primary engagement plane, and each secondary engagement element is V-shaped when viewed in a cross-section perpendicular to its respective secondary engagement plane, characterised in that, the insert has four secondary engagement elements and each secondary engagement plane forms an acute engagement angle (α) with the primary engagement plane.