I have a vintage 70’s Gucci bracelet that is stamped Gucci S Italy. The S is outlined by a diamond shape?

Here\’s a question that was asked about Vintage Diamonds:
I am trying to determine whether the S means sterling silver, stainless steel or plated silver. The bracelet has no tarnish on it and it is from the 70’s. It also has not been used.

What does the S mean? I want to sell it and want to represent correctly.