When painted, colored, or stained glass windows or parts thereof, are claimed free of duty under subheading 9810.00.10, Harmonized Tariff Schedule of the United States (19 U.S.C. 1202), the Center director may, at his discretion, require appropriate proof that the importation was designed by, and produced by or under the direction of, a professional artist, and that it is for the use of an institution established solely for religious purposes.