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I don’t know for sure who made this piece, but it’s modern, and probably not earlier than the 1970s.
The rest of the mark says “Ceramica Conimbriga” and ”Sec. XVII Rosario”. Conimbriga pottery is made in the vicinity of the ancient Roman settlement of that name in the municipality of Condeixa-a-Nova. A number of factories sprang up in this area in the 1960s/1970s, producing hand painted pottery inspired by traditional Portuguese and Hispano-Arab designs of the 17th & 18th Century. Hence the “Sec. XVII” (for Seculo XVII… ie 17th Century). Generally, export began in the 1970s (and this is an export piece since it has “hand-painted” in English.
“Ceramica Conimbriga” is a generic for the type of pottery. I’m not aware of a company that has
exactly that name but, in Condeixa-a-Nova itself, the largest producer is “Estrela de Conimbriga” (founded in 1975) and also “Ceramica
de Conimbriga” (founded a little earlier).
It might be that “Rosario” is a style/pattern name or the actual name of the company… in which case it might be “Ceramica Rosario” (founded 1964) who operate from Serra d`El Rei about 100 miles south of Conimbriga.
This is typical “Conimbriga-ware”:
https://www.estreladeconimbriga.com/en/products/pottery
