My thanks to Rongli for the ink sample.
St Dupont Turquoise is a bright turquoise on the blue end of the blue-green spectrum of turquoise. It is a relatively wet ink but it dnd’t write well in my Pilot Myu 701 F despite it being a dry nib like this TWSBI Mini 1.1mm nib. In the Myu 701, it writes but the feedback it produces with this ink is a little too much to be enjoyable. I think it is just a case of bad ink and pen combination, no fault of the ink really. That said, even in the F Japanese nib it has shading. With the right pen, this ink will be a great shading ink.