The invention relates to tracer particles for product identification and/or authentication. When incorporated into a manufactured item, that item can be subsequently authenticated by detecting the tracer particle. The tracer particles of the invention are etched with markings, and in some embodiments, are manufactured with materials that are generally recognized as safe (GRAS). 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, baby formula powder and liquid bulk materials. Other applications include forensics, such as in explosive materials.