I saw similar labels in the LR. Just wasn't sure if this would be 50s or 60s? The whole thing is a lovely heavy nylon in 2 layers.
Nylon was commonly used in nightgowns in the 1960s. Also keep in mind that synthetics became more common in every garment in the 60s.
that empire waistline is reminiscent of the 60s. i've had some Shadowlines in the past that we did ok with...i was surprised when i first saw the label i immediately thought 80s by it's look. but yes, they've been around a while now. that's a really pretty set.