Thomas E Dugan became manager of National Glass in 1899. The Dugan brothers (Thomas and Alfred) operated the plant until 1904 when they became the owners and the Indiana, Pennsylvania plant became Dugan Glass Company. In 1913 the Dugan Brothers left and the name was changed to the Diamond Glass Company which operated until 1931 when the plant was destroyed by fire.
The production of the question marks pattern spanned nearly a decade from about 1910 to 1920 but was made in only several shapes. This lovely two-handled bonbon on a stem measures 5" across, 7 1/2" from handle-to-handle and 3 1/2" in height. The pattern is on the interior with the exterior plain. The iridescence of this piece is fantastic, with beautiful dark blue, rose and copper all perfectly mixed for a great contrast. The coating is so dense I cannot tell if the base glass is amethyst or blue. The underside of the base looks almost black, so it is probably dark amethyst glass. There are no cracks, chips or repairs. If you enjoy carnival, you will love this piece.