The invention provides a method and system for labeling items, wherein the labels contain digital information and can be read when desired. The coding of the labels is done by choosing specifically engineered nano-particles, micro-particles, or liquid material in the form of "ink." The particles are designed to contain materials with distinguishable NMR (nuclear magnetic resonance) or NQR (Nuclear quadrupole resonance) frequencies and are combined in sets to encode digital information. The NMR/NQR label particle sets are printed on the item to be labeled, or on a label substrate which is then attached to the item to be labeled. In one embodiment, the printed NMR/NQR label consists of an array of spots, each of which may encode one or more digital characters. These spots can be detected and the digital information in the label can be read using a suitable magnetic resonance detector.