I shopped at the same Downtown Crossing Albert's as Leggypat in the 1970s. At that time, Albert's still carried a full line of FFNs and RH&Ts in 100% nylon...anything that would have been available in the 1950s. As I recall, only their seamless stockings were velvetized.
My favorites were their seamed stockings. Their "Classic" 15 denier FFNs were only $1.75 a pair as I recall. So I wore them quite frequently. And their "Favorite" FFN walking sheers were only $1.50 a pair. I think the velvetized RH&Ts were only a dollar a pair! Of course, this was in the late 70s when stockings weren't too popular in the US. The older ladies who ran the shop were amused that a young gal in her 20s like me still wore gartered stockings, and especially seams. I had fun shopping there.