Samples taken in accordance with § 151.52 shall be promptly forwarded to the appropriate Customs laboratory for testing in accordance with commercial methods. An authorized CBP official may secure from the importer a certified copy of the commercial settlement tests for moisture and for assay which shall be transmitted with the commercial samples to the Custom laboratory. If the Customs tests are not in substantial agreement with the settlement tests, the Customs laboratory director shall review his tests. The Customs tests shall be used in determining the final duties on the merchandise, except that the settlement tests shall be used if, in the opinion of the Customs laboratory director:
19 C.F.R. §151.54