machine acid etching almost certainly - though improved picture would help - try a uniform dark background with varying light intensity until you lose this brownness.

As to date, could be anywhere from 1890 to 1950 - the answer might depend more on the extent of wear, if any - a very commonly made type of glass/decoration ............... but of course very useful - unless like me you're on a dry January - only four days to go!! Regret to say you will never find the maker, and you'd be lucky to even get the correct decade - these things exist in really prodigious numbers.
Again, you don't provide a size, but I'm tempted to suggest these are for either sherry or port perhaps.
