Identifying SW 417 Mark on Italian Gold Jewelry: Is it Real Gold?

Question
I have a 22" gold necklace, on the clasp is has the mark "Made Italy" and on the reverse side, SW 417.  I have been trying to find this mark online under the assumption that it is a hallmark of some sort but I am not sure.  I would like to know if this is real gold, and if it is, what carat it is.  Thank you.

Answer
Good morning Jeremy,
    Gold has many purities as you are probably aware of. Different countries produce their gold products in varying degrees based largely in part to their economies. Italy for one, and encompassing all of Europe for that matter are the most exacting in their purity standards. .417 is 41.7% pure gold or 10 karat, .516 is 14 karat, .750 is 18 karat to name a few. However I am a bit skeptical of your item being 10k due to the fact that a lot of Italian gold coming direct from Italy is 18k. Now your item could have been made on Italian machinery which is the best in the world in another country, even in Europe. Your best bet is to bring the item to your local jeweler to have them do a nitric acid test on the neclace. This will not harm the piece in any way and it will assure you of its gold content. Hope this helps a bit.

Steve Kretser