People often ask what defines an item as an antique but the answer is neither simple nor straightforward.
Many people say an item has to be at least 100 years old to be called antique. These days though, there seems to be a growing number of people who now consider 50 years to be the cut off point.
In truth, there are many contributing factors apart from age. Things such as the type of item, the quality of the piece, the maker, its rarity and any historical significance attributed to it all have a bearing.

Antique Cranberry Font Oil Lamp with Victorian Shade
Are oil lamps antiques?
With regard to oil lamps, the period of popularity and peak usage was less than 100 years. This comparatively short period spanned from the mid 19th century until the early 20th century. The era began in the late 1850s with the first oil drilling operation in the USA. This made coal oil (kerosene) readily available as a lighting fuel. It was a cheaper option than whale oil and much safer than burning fluid. In all but the most remote locations, the eventual widespread use of electricity had replaced kerosene as the lighting source of choice by the 1940s.
While the lamps from the latter part of the period are less than 100 years old, most of them are still generally considered to be an antique as they were manufactured within that “golden era” of kerosene lighting.