The term “vintage” is used often in the costume jewelry world, probably not always accurately. I recently offended a customer by calling a piece of costume jewelry from the 1940s vintage….she said that if the jewelry was “younger” than her then it could not be vintage!
The term “vintage” can be used in two ways. First, it means that the jewelry represents the recognized style of an era. For example, a mid-century vintage piece of jewelry should have the characteristics that are common to mid-century jewelry.
The second and more commonly used “vintage” means that the jewelry is pre-owned and is not new. In my opinion, a piece of jewelry becomes vintage when it has been around long enough to come back into style. This happens in the fashion world about every 20-25 years. I would certainly call jewelry from the late 1970s-early 1980s “vintage” as it has become collectible.
Antique jewelry is defined as jewelry that is around 100 years old. Right now, I’d put the dates for vintage between 1920-1980. More here.