A method of evaluating the quality of a color reference card having multiple color reference fields. The quality refers to whether the color reference card is usable for a method for determining concentration of analyte in a body fluid and/or to the degree of suitability or reliability of the color reference card for use with a method for determining analyte concentration in a body fluid. In the inventive method, an image is captured of at least a part of the color reference card using a mobile device camera. Measured color reference values are determined from the image for one or more of the color reference fields and a relationship between one or more of the measured reference color values and corresponding known reference color values is determined. The determined relationship is used to assess the quality of the color reference card. A kit and mobile device are also disclosed.