Despite the rapid profusion of new branded and proprietary diamond cuts in recent years, considerable confusion exists in the trade about the important differences between trademarks and patents. Proprietary brand names can be protected by trademark registration (typically noted by a registration [®] symbol next to the brand name), while proprietary designs or products can be protected by patents. Both methods have important limitations, and the recent history of cut designs reflects the importance of protecting a valuable diamond cut. A study of the proprietary designs currently in the marketplace revealed a preference for trademark protection over patents, though many designs appeared to have no patent or trademark registration. A list of recent proprietary designs is given in the Appendix.