Two purple dyes are described in the Hebrew Bible: <i>tekhelet</i> (a blue-purple) and <i>argaman</i> (true Tyrian purple). The identity of the shellfish from which the dyes were obtained, much confused in the past, has now been clarified by analysis and technical studies. The discovery of Tyrian purple and <i>tekhelet</i> is described, as well as the technical details of the chemical composition and chemical reactions (with formulae) of the products of the shell fish. The biochemistry of the dyes is described. Insect dyes replaced the shellfish dyer, and the various insect sources are detailed. The paper is a good short summary of previous papers on the subject to which references are given. -- AATA