A “white-silk girl” is a virgin
A “white-silk girl” is a virgin; one who is not a virgin is sometimes referred to as a “red-silk girl.”
This need not refer, literally, of course, to the color of their garmenture.
White-silk slaves, as you might suppose, are very rare. There is apparently a market for such. The most expensive of such slaves, as I understand it, are those which have been raised from infancy in seclusion, kept literally in ignorance of the existence of men. Then, when they are of a suitable age, they are purchased, unbeknownst to themselves, by unseen buyers. Later they are drugged and removed from their familiar surroundings, to awaken in new surroundings, of the buyer’s choosing.
Witness of Gor, p. 232