To get an accurate appraisal for an antique lamp online, contact an appraiser who specializes in lamps, and get permission to send detailed photographs and dimensions of the object, as well as the applicable fee, to him. Also include any information about the provenance of the lamp, images of any unique details or characteristics, and clear photographs of any maker's marks. The appraiser should respond with a written appraisal that includes the value and history of the piece.
To get an in-person appraisal, look for a professional who is accredited by the Appraisers Association of America or the American Society of Appraisers. Expect to pay the appraiser a flat fee or hourly rate. Once the appraisal is complete, the appraiser should issue a letter stating the value of the lamp and the procedure used to determine its value. Some appraisers may use insurance values while others may give an estimated fair market value of the piece.
To find free appraisals, look for oral appraisal events offered by reputable auction houses that are open to the public. Typically, the auction house may call these events valuation or appraisal days. Avoid taking your lamp to an antique store for a free appraisal due to the conflict of interest. You can also use lamp price guidebooks to do your own appraisal of your lamp's potential value, and then decide if you want to pay for an appraisal.