Antique glass lamps are practical additions to the home, since they are useful when the electricity is off. Glass lamps also are fashionable decoration. Kerosene lamps are the most common collectible style of antique glass lamp, and these beautiful essentials from the past have identifiers to distinguish them from reproductions. Whale oil lamps also were made of glass, but are more difficult to find.
Check the brass collar by removing the globe and the burner. Under the burner, old lamps have a brass collar with internal or external threads. Newer lamps do not have a brass collar.
Examine the glass. Many of the old lamps are pattern glass, or glass with a pressed design. The glass is heavy and has a seam up each side. Some have four seams, and are four-mold lamps.
Feel the glass. Reproduction glass lamps feel greasy or slick and the glass is not quite smooth. Reproductions often have little globs of glass left over in the manufacturing process found at the seams or under the base. Antique glass is not slick, but is smooth. If you cannot tell, take a piece of cellophane tape and stick it to the glass. Tape does not stick easily to reproduction glass.
Look at the globe or chimney. Old glass globes are blown glass with no seams. Chimneys often are an unusual shape or have etching or writing on the glass. Old globes or chimneys may show minor flaws from the blowing process.
Examine the burner. Old burners are brass and often have a patent number and maker information. Use a magnifying glass and check for a number, date or maker. Check the flat part of the stem for written information.
Look for quality and extra handwork. Turn the lamp base over and see if there is a design on the bottom edge, and look for a design inside the base. Some lamps have a rope design at the bottom.
Expect two colors of glass or unusual combinations on antique glass lamps. A marble base with a glass bowl and stem is a common combination in antique glass lamps.