Vintage Teal Sleeveless Sweater Jacket

This is a lovely vintage over layer! I am not sure of the year on it and there is no brand tag. The size tag on it marks it as a size 8 although it is likely a bit smaller. There are no rips or tears in it, however it does have a few small rust stains on it that I haven’t been successful in removing. The most noticeable and largest one is shown in one of the photos.