Blue was a rare, expensive color in ancient times, whether it was derived from lapis lazuli mined in Afghanistan some 6,000 years ago, made by blending copper with other elements throughout the Middle East and in ancient China, or mixing an extract of the indigo plant with clay and resin by Mayans in Mesoamerica. Now, a centuries-old tradition of dyeing blue cloth with delicate patterns in parts of eastern Europe has been recognized for its cultural importance by UNESCO. Faith Lapidus reports.