I was thinking maybe 70s? It feels quite delicate so i was thinking maybe earlier but i'm not sure to be honest, the neckline has some "golden" or metallic floral embroidery, could it be golden wrapped thread?? Thanks for looking!
I've seen ribbon trim like that called jacquard. Yours is a rather simplistic design but a pretty purple. I would simply call the thread "metallic". Edit: Similar trim is still widely available (and inexpensive) today: Another Edit: I would doubt that your cute shirt is earlier than 1970s.