J.Herbin  Ink bottle, La Perle des Encres series Yellow ink (Yellow button gold)

For fountain pens and glass pens Water-based, 30ml
Bouton d’or (Yellow button gold): this color is related to the flower of the very same name. Based on a children’s game that consist of putting the flower under one’s chin, if the latter becomes yellow it means this person likes butter.
This ink has an intense and bright yellow hue.