Indexable cutting insert with indexing marks

An indexable cutting insert for use in combination with a toolholder, the cutting insert comprising:

• a cutting insert body having a rake face of a circular shape and a flank face of a continuous arcuate shape wherein the rake face and the flank face intersect to form a cutting edge;
• and
• at least one of the flank face and the rake face having a visually perceivable indicia thereon extending along a diametrical line or substantially in parallel with a central longitudinal axis of the cutting insert so as to indicate a plurality of discrete indexable cutting positions of the cutting insert relative to the toolholder;
• wherein the indicia comprises a plurality of marks, each pair of adjacent marks is disposed at an included angle, the magnitude of the included angle satisfying the following relationships:
• sec α=r/(r−c), and
• (n)(α)=360°
• wherein
• α is the included angle,
• r is a radius of the circular rake face,
• c is a distance along a diametrical line between an intersection point and a chordal point, wherein the diametrical line is defined by a radial line extending from a point at a geometrical center of the top rake face to a point at the cutting edge, wherein the intersection point is a point defined by the intersection of the diametrical line and the cutting edge and the chordal point is a point defined by the intersection of the diametrical line and a chord, the chard being perpendicular to the diametrical line and including points defined by the intersection of the cutting edge and two adjacent diametrical lines located on opposite sides of the diametrical line, and
• n is a whole integer.