Old oil lamps can be a fun addition to your home or a source of a profit, depending on the condition and age of your lamps. While you can tell what shape the lamp is in by looking at it, you probably won't be able to find much manufacturing information on antique oil lamps. The best way to get an exact date of manufacture is by having an appraiser view the lamp. You can also educate yourself on oil lamps that resemble yours to better understand the antique lamp market and the changing styles of lamps throughout time.
Inspect your antique oil lamp from all sides, looking for special markings, signatures or other clues to the lamp's age and manufacturer. These may include stamps, insignia or a manufacturers' name near the wick winder button. Oldcopper.org displays many of the markings found on antique oil lamps in a list that's broken down by manufacturer. Note any dings, scratches or other markings. Use a magnifying glass to get a closer look.
Photograph your oil lamp in natural light. Take care not to get a glare; you want to show as much detail as possible in the photo. Get pictures of the lamp from all angles.
Research lamp appraisers near you using the American Society of Appraisers website. If there are no appraisers near you, find lamp appraisers who can offer an appraisal from photographs only. An in-person appraisal is best because the appraiser can examine your lamp from all angles instead of relying on a few images to offer the most accurate age assessment.
Call the appraiser to set up an appointment. If you can't find an in-person appraiser, email appraisers in other locations and arrange for an appraisal via photograph.
Research any clues you found while inspecting your lamp. If you know the lamp's manufacturer or approximate age, find books about oil lamps from that era. Catherine Thuro's "Antique Kerosene and Oil Lamps: Volume 1" is one good reference book. Eagle-emporium.com displays images of many different styles of old oil lamps. You may be able to narrow down the style and time period of your lamp by finding similar lamps on Eagle Emporium.
Discuss the age and value of your lamp with the appraiser. Ask your appraiser what your lamp is worth and how that worth has changed over time. Find out what the appraiser's recommendations are for lamp insurance and routine maintenance, such as cleaning or polishing. If you intend to sell your lamp, ask the appraiser for recommendations of buyers.