Exhibit 99(b)

                                Certification By
                  Richard L. Bergmark, Chief Financial Officer
                            of Core Laboratories N.V.
                          Pursuant to 18 U.S.C.ss.1350

         I, Richard L. Bergmark, Chief Financial Officer of Core Laboratories
N.V. (the "Company"), hereby certify that the accompanying report on Form 10-Q
for the quarter ended March 31, 2003, filed by the Company with the Securities
and Exchange Commission on the date hereof pursuant to Section 13(a) of the
Securities Exchange Act of 1934 (the "Report") fully complies with the
requirements of that section.

         I further certify that the information contained in the Report fairly
presents, in all material respects, the financial condition and results of
operations of the Company.



                                            /s/ Richard L. Bergmark
                                            ---------------------------
                                            Name: Richard L. Bergmark
                                            Title: Chief Financial Officer
Date: May 15, 2003