The value of old ceramic insulators is determined by the condition of the insulator, its color, age, manufacturer and the demand by collectors. Insulators that were made in a limited quantity are high in demand and value.
Insulators with mottled glazes, fingerprints and bright colors, early threadless insulators, and old insulators from historical power lines are most prized. Pin-types, johnny balls or guy wire strains, suspensions, and radio strains are highly collectible styles. Insulators by manufacturers such as Greeley, Chester, O'Brien Patent, EC&M, Tillotson, Liquid and Zicme are more desirable due to their limited production and availability, making them generally worth a premium price.