I have customers who confuse laboratory certificates with appraisals and that is entirely understandable. A laboratory report is independent, third party verification that the gemstone in your jewelry (ring, for example) is, in fact, really a (for example) diamond; that it has the measurements and carat weight specified in the report as well as the color, clarity and cut specified. The laboratory report usually describes the single most valuable part of the piece of jewelry being appraised but it does not assign a dollar value to it. Some laboratories do have partnerships with appraisal firms and provide an appraisal for the gemstone by itself as a separate document.
But most appraisals are for finished pieces of jewelry and so there is always the mounting which adds value and sometimes side stones which do as well. If the piece is designed and manufactured by a famous and popular designer, that can add significant value, especially if the piece is signed.
So, a well done appraisal includes most of the information that is on the laboratory report but includes additional information as well on the mounting, side stones, designer, etc. and assigns a dollar value to it. That dollar valuation can vary significantly depending on the purpose of the appraisal; but that will be the subject of a future post.