The design of the first piece is from Mdina - Crystal Blue Stripe and with the very heavy use of silver chloride and the jewell-like blue, would suggest a later execution of this design rather than early - there was a later period of the silver salts being very heavy in these, but the design itself is one of Michael Harris' and has been in production almost from the start of Mdina.
I don't know why the inscriptions are there or what they mean, but perhaps they might be pieces from when Gozo was being set up and designs modified for that purpose? (in the '80s, which would be about right for the heavy salts and the jewell-like blue)
The small size is interesting, but I've checked it against a surface decorated "miniature" from Mdina and it is bigger than that, so I don't think it's part of that range, but I do have a Mdina small flat disc bottle, which I think is this size, in the more plain blue with the silver chloride ochre streak design. (I can't find it atm.)
The last piece shown, with the browns and reds, over a crizzle background, is a very unusual thing, I've not seen one before, it's possibly an early experimental thing...
