Book excerpt: Samar Najm Abul Huda's translation of Ahmad ibn Yusuf al Tifaschi's study of gems. Born in 1184, Al Tifaschi first learned about gems from his father, and augmented his knowledge through readings of Aristotle, Theophrastus, and Pliny, as well as through extensive travels to mines and trading centers. In 1253, he wrote what later became known as the most 'methodical and complete' work on precious stones. Gemologists of today are still astounded by the advanced observations that Al Tifaschi made in this work.