Electronic payment systems based on anonymous coins have been invented as a digital equivalent to physical banknotes. However, von Solms and Naccache discovered that such anonymous coins are also very well suited to support criminals in blackmailing. In this paper we present a payment system, which has an efficient tracing and revocation mechanism for blackmailed coins. The used tracing method is based on the idea of marking coins similar to marking banknotes with an invisible color. In contrast to previous solutions our payment system is unconditionally anonymous and thus protects the privacy of the users.