Yes, it has two T's in PERETTI.These pendants have been made by Tiffany for a long time. The way they are marked has changed subtly over time. Some say 18k, some say 750, Spain. The item is fairly old, probably 20 yrs but it doesn't look suspicious. It does say Peretti with 2 ts, right?
The lack of soldering on the ring of the clasp that holds to the necklace chain had me concerned. Maybe the clasp was changed through the years...?
Many thanks!