Unfortunately, I know of no definitive listing of all the "J Weights" made by John Deacons. The lists and images shown in John Simmonds' book Paperweights From Great Britain 1930-2000 do not include anything that fits with the weight you show (but I could have missed something). In that book, there are no descriptions, for example, in respect of "J weights" that were made solely for the US market.
Probably the only way to be sure about the weight would be to ask John Deacons. (I don't have his contact details, but some folk who look in here may do and may be able to email you directly.)