I think I'm correct in saying this is neodynium glass
Yes Sue, 100% correct. The last side views image taken under fluro lamps, the rest were afternoon sun. Distinct colour change.
Internet slow here tonight, but I'll take a look through image search terms your suggesting when I can on a faster pooter, maybe tomorrow. Can't say I've seen similar yet, in my lookin.
The lack of any acid etched or engraved manufacturer is problematic for ID.
Caithness I've seen, very few indeed, have had acid etched ID on base.
Was that treatment standard over the years?