Hi
Both the Liskeard and the Langham weight will sell on E-bay without problem - I will put my hand up for the Liskeard if you are thinking of selling !!!
Liskeard Glass was founded by Duncan Randall in 1973. Its main product was tableware glass in two ranges named after the local rivers. Some paperweights were produced but they were usually simple "tourist" weights - they are characterised by the impressed LG mark. Liskeard also did private commissions such as weights with a "y" or "st" impressed" Yelverton and St. Tudy.
Liam Carey was taken on as an apprentice in the mid 1970’s at the age of 16. Liskeard continued until 1978 when Liskeard Glass was sold to someone from the Isle of Wight although not the Harris family. It was renamed Liskeard Studio Glass and Liam worked for the renamed studio until 1983.
He then bought out the owner and renamed it Merlin Glass - he still has a shop in Liskeard but most of his output - mainly door and cupboard knobs is sold via the internet.
Langham glass was founded in 1979 in Norfolk and is run by Paul Miller.
Re the unidentified weight - I would put my money on Mdina - a factory on Malta started by the Harris family .
Hope this helps
Regards
Derek