Hello Hazel,
a nice weight with some age indeed - the author Peter von Brackel recorded weights like your's in the category of post classic weights (i.e. roughly 1850/60 until 1900) and he only could distinguish a couple of groups with common features, without being able to differentiate a certain source for each group.
So those weights are mostly filed under post classic, from Bohemia, Silesia, Saxony,Bavaria, Thuringia or Lusatia- the youngest identified of them were made in Lauscha/Thuringia (some dated around the 1930ies and 1940ies). Surely the makers had inherited some knowledge about making millefiori, but the domes are sometimes irregular and the glass is sometimes of inferior quality compared to classic pieces of the mentioned areas.
Many of those weights are found in the USA, where German and Bohemian immigrants were coming in around 1850/60, and possibly brought the weights along as a keepsake from their home country.
Hope this helps, best wishes Erhard