On this occasion—the celebration of Richard T. Liddicoat’s 50 years guiding Gems & Gemology—it is fitting to review his enormous impact on the field of gemology. This includes the development of GIA’s education program, the creation of the quality-grading system for polished diamonds that is now accepted worldwide, numerous contributions to the gemological literature, involvement in new gem-testing techniques and instruments, and the establishment of a formal research program. His greatest achievement, however, has been his personal influence on the professionalism and ethical standards of the international gem and jewelry industry.