Argento is a star which was mentioned in the first book. It was on Sophie's list for her star bottling assignment. It has a metallic-toned light, and was much more difficult to find than any star on Dex's list, causing Sophie to strain her memory looking for it. It is unknown what color it emits, though when seeing all the bottles lined up Sophie notes that they were silver, gold, black, white, copper, and green. Along with Auriferria, Pennisi, Merkariron, Styggis, and Achromian two lines are formed pointing at Elementine.