For centuries, dyed fabrics ranked among the most expensive objects of the ancient Mediterranean world, fetching up to 20 times their weight in gold. Huge fortunes were made from and lost to them, and battles were fought over control of the industry. The few who knew the dyes' complex secrets carefully guarded the valuable knowledge. The Rarest Blue tells the amazing story of tekhelet, or hyacinth blue, the elusive sky-blue dye mentioned 50 times...