These plates are usually dated around 1828, give or take a couple years . Heavy thick lead glass. The edge thickness varies between 1/2 in. and 1 ln. unlike later [lacy] plates and bowls which use a cap ring in conjunction with the mold. The cap ring prescribes the thickness of the rim and sometimes the design as well. Last photo shows a later sauce dish molded using a cap ring and one of these plates and the difference in the edge.