I am frequently asked "How do I know if an outfit is vintage or reproduction?"
After you have collected for a while you will begin to get a feel for the real thing. But sometimes it is really hard to tell the difference. One thing to look for is octagon shaped tulle. Mattel used it for neck, arm hole and hem facings; hat overlays and linings; dress linings, overlays and skirts; slips. YKK zippers are hand sewn in place. Linings are detached as seen in Red Flare coat. After 1965 seams are serged and they are not in the earlier outfits. However, in a reproduction of the pre 1965 outfit the seams are serged. Jewelry items have distinctive looking hooks and loop closures. They will usually have some degree of tarnish. Some hats are made of wool felt and have grograin covered bands that hold it on the dolls head.
If in doubt compare pictures of different listings.
I hope this has helped. Happy Barbie hunting. Thanks, Vicki