Exemption for precious metal catalysts retained when remade or refurbished, preventing excise duty on reworked catalyst articles. The circular clarifies that the exemption from excise duty for articles and unfinished or semi-finished forms of precious metals under Chapter 71 is unconditional and applies irrespective of whether those goods are manufactured first time or re-made, re-conditioned, refabricated or recovered from used or spent catalysts, and therefore such goods should not be charged duty under the separate manufacture entry for added material or processing.