What is an antique lamp? I personally like the generalized definition which states that it is lamp which is from a bygone era. This places the term outside the legal arena and into a subjective personal usage which is where we commonly incur the term. "Era" is general perceived and is defined as a long indefinite time period which also works out perfectly for this generalized definition. I do not perceive any problems with this working definition especially since any identification of an "antique Lamp" is fairly useless anyway without some time period designation normally in the form of "circa year". i.e. "circa 1905" which literally means " about the year 1905. So I will use the term antique lamp on this basis and often substitute it with the term "vintage".
Determining the age of an antique lamp involves numerous factors. Many times the lamp itself will promptly place its origin in a certain time frame due to well known styles from specific time periods. Sometimes a component of the lamp is marked with a date, letters, numbers, graphics or other markings which places its origin in a certain time frame or within the context of certain manufacturers known during a specific time period. Old catalog photographs, old newspaper and magazine advertisements, museum photographs and various antique lighting books and publications are reliable resources from which to compare antique lamp styles in order to confirm the origin date and manufacturer. However some of these publications have a limited availability and are often quite expensive. There are numerous auctions that have listings for antique lamps but often their descriptions are either very limited or unknown and sometimes embellished. It is not unusual to find many of these auction listings completely erroneous and misleading especially in regards to attributing unmarked antique lamps to certain highly collectible manufacturers. These venues in general are not reliable sources for authenticating or identifying antique lamps. There are some exceptions to this caveat, namely certain reliable and professional auctioneers who have a long and reliable history of accurately listing antique lamps.
Generally, there are very limited reliable sources for identifying antique vintage lamps. Among the most reliable sources are experienced professional collectors, dealers and appraisers who have amassed an extensive knowledge base for certain vintage lamp manufacturers.
Many of the most experienced and knowledgeable resources are regularly inundated with requests from individuals asking for all sorts of information regarding their antique lamps. Many of these requests are in the form of "What is it worth? "How old is it?" "Who made it?". There are plenty of individuals who will offer free quick answers and advice to these questions without regard to the time tested principles of professional appraisal. These answers are usually worth just what they cost. A genuine antique lamp appraisal determines identity and value through lengthy and careful study and actual comparisons of real transactions of the same or similar vintage lamps. The resulting appraisal not only gives a true current market value (always changing) of the antique lamp but also provides detailed historical information regarding the antique lamp, the lamp manufacturer and sometimes general historical information of the period.