Coca Cola Jean Skirt

If it was made in the US (most denim was during this time) there will be an ILGWU union label inside. This will at least give you an idea of when it was made. Here's a good guide to use http://vintagefashionguild.org/label-resource/ilgwu/

I collect vintage Levis, Wrangler, Lee, and other denim and have never heard of a coco-cola skirt. I've seen denim Pepsi jackets from the late 70s early 80s that sell for around $20-30.