Thank you for showing this delightful (and undoubtedly rare) piece, Roy, though I think you may have a typo in the registration date for the design.
I can’t find a Berens, Blumberg & Co. design registration for 13 October 1851 (or any other glass design registration for that matter), but Jenny Thompson (page 95 of ‘The identification of English Pressed Glass 1842-1908) shows that on 31 October 1851 – Parcel 4 Berens, Blumberg & Co. of St. Paul’s Churchyard, London registered design number 81217 in Class 3: glass.
This is confirmed by The National Archives online Design Registration summary at http://discovery.nationalarchives.gov.uk/results/r?_q=registered+design+81217
where the design description is for a ‘Paper Weight’ [?].