The invention relates generally to tracer particles for product identification and/or authentication. When incorporated into a manufactured item, that item can be subsequently authenticated by either detecting, or failing to detect, the tracer particle. The tracer particles of the invention are magnetically attractable, with micromarkings, and in some embodiments, are manufactured with food grade materials and of a particle size suitable for ingestion by humans. The particles can be analyzed qualitatively or quantitatively. In other aspects, the invention provides methods for the manufacture of the tracer particles, and in other aspects, provides methods for using the particles. Examples of products that can be tagged using the tracer particles of the invention include pharmaceuticals, animal feeds or feed supplements, and baby formula. Other applications include forensics, such as in explosive materials.