When i sell my diamonds, is a certificate the same thing as an appraisal?

No. A diamond appraisal is the opinion of an individual appraiser as to the quality of a diamond and his/her opinion as to the monetary cost of replacing the stone. An appraisal is useful only as a tool for the insurance industry when a customer needs something replaced due to loss or theft. Appraisals are typically far above the actual retail cost of a diamond. In contrast, a certificate is issued by an independent laboratory that has had one or more staff members evaluate the stone for its specific quality. A certificate contains no price estimates; it is simply the assessment of the lab as to the exact quality of the diamond you are selling.