Optically variable ink for obtaining a color shaft between two distinct two colors at first and second angles of incident light comprised of an ink vehicle and optically variable flakes disposed in the ink vehicle. The optically variable flakes are comprised of a multilayer thin film interference structure having first and second parallel planar surfaces. The optically variable flakes have physical dimensions such that when the flakes are measured in directions parallel and perpendicular respectively to the planar surfaces an aspect ratio of at least 2 to 1 is provided. The multilayer thin film structure is of symmetrical design and includes a metal reflector having first and second surfaces parallel to the first and second parallel planar surfaces and at least one period disposed on each of said first and second surfaces of the metal reflector. Each period is comprised of a dielectric layer with an index of refraction of 1.65 or less and a semi-opaque layer.