Maker marks on carnival glass are essential for identification and valuation. These marks evolved over time, making them useful for dating pieces as well. Marks can include stamped logos, impressed marks, painted marks, paper labels, or incised signatures.

To identify a mark, examine the piece carefully under good lighting. A magnifying glass can help with small or worn marks. Compare what you find against reference guides — or submit photos to InstAppraisal for AI-assisted identification.