A security feature and method for verifying the authenticity of commercial paper. In one embodiment, pearlescent ink is added to a portion of commercial paper stock. A recipient can then tilt the commercial paper stock to view the pearlescent ink mark, design, or spot from different angles, causing the pearlescent ink to appear different colors and verifying the authenticity of the commercial paper. Further, according to another embodiment, thermochromic ink is applied to a portion of commercial paper stock. A recipient can then apply heat to the commercial paper stock in the area of the ink mark, thereby causing the thermochromic ink to disappear or change colors.