Vintage 60’s Nelly de Grab New York Long Maxi Skirt with Side Slits

Vintage 60’s Nelly de Grab New York Long Straight Maxi Skirt with Side slits Good vintage preowned condition - tags are a little worn and there is a stain on the inside hem of one of the side slits (last photo) Size S/M - no size tag but this is my best guess. Waist is elasticized and can expand to about 18”. Based on the ILGWU union tag, I believe this is late 50’s / early 60’s. Fabric is some sort of brushed synthetic, not silky and not stretchy. Unique vertical pattern in brown, tan, and rust orange on ivory background.