*Lustreware refers to a style of pottery decorated with metallic oxided glazes which provides an iridescent effect. The process involves two firings: the first adds the color, the second, the *lustre. Please do not mistake reflections for imperfections, I do not see any. The color is amazing. Difficult to get photos because it is so reflective. *The mark on this item indicates it was made by the Ohio Pottery Company, likely in the 1920s or 1930s. The diamond-shaped logo with "OHIO" inside is the company mark. The text "MADE IN U. S. A." confirms its origin. The number "80" likely refers to the specific mold or style number of the piece. The Ohio Pottery Company was known for producing dinnerware and other ceramic items Vintage lusterware from Ohio includes pieces by the Pearl China Co. (vases, bowls) and Royal Rochester/Fraunfelter (tea pots, casseroles). Styles: Items often feature metallic, shimmering, or iridescent finishes in gold, silver, or blue. * Information gleaned from the Internet, I am not an expert. In the Sugarbowl there are a couple little marks that look like they would be from the factory in the making of the piece. See last two photos.