I recently used the appraiser that you mentioned, since as far as I know they are the only independent appraiser in Dallas. The only thing that I really wanted to know was if the cert matched the stone (it did). I'm having the stone set right now, and I plan on taking it back to them once it is set to get an appraisal for insurance purposes. She told me that she will also verify that the stone was not switched during the setting process. I would recommend them for appraisals. My cost was $75.