Dating a lamp by Achille Castiglioni  

Could I please have some assistance with a lamp I purchased?

At a sale, I took home a lamp that was made by FLOs in Italy.

I am curious to know how one dates the production on an Arco lamp produced by FLOs - I thought there may be signs as there are with Herman Miller labels that would assist in nailing down the period produced.

I have emailed FLOs twice and received poor information in return, and I have emailed the Italy office, though no answer as yet.

The only other information I can provide would be regarding a marking I have seen on some lamps on google that show a signature of sorts on the rod that enters the Marble - mine does not have that "signature".