salts come in many guises - although don't recall having seen an amethyst example with gilding - but no reason why they couldn't be used as such. Don't usually find this many salts remaining together - more usual to find them as singles or pairs.
Gilding on rims, feet and bodies is a decorative feature of the early C19 - finger bowls, liquid condiment bottles and decanters are quite common examples.
Had these been of an early C20 manufacture, might they have been liqueur glasses perhaps, or for some specific cultural use. Can't quite see - are these rims ground flat, or fire polished (slightly rounded)?...... believe ground rims are more likely to be non-British.
Sorry this is no help, but if pushed I'd suggest Continental, although date is eluding me really, but C19 (somewhere) is probably correct.