This is probably no earlier than the 1960s when there was a renewed interest in stained glass fixtures. It is vintage rather than antique. Even though it's probably a stock ceiling canopy, sometimes there will be a sticker or label in there, but it's pretty common for these not to be marked.

Here's a similar one on ebay from 1970

$99

I'd search there for 'vintage stained glass chandelier' if you cannot find any marking on yours.

ebay listing