Just pick up these, i believe knil artillery buttons.

Why KNIL? Firstly the TNI never used this kind of buttons before. And secondly the shape is similar in these photos:
KITLV Digital Media Library - Portret van de heer Bruyman, kapitein der marechaussee, op Java
KITLV Digital Media Library - Portret van een Europese man in Nederlands-Indi
KITLV Digital Media Library - Portret van een militair van het KNIL op Java
Note: the site misunderstood the knil artillery collar emblem as the mainland marechaussee (military police) emblem.
But still, i can’t judge the exact dating of these buttons. So is there anyone knew how old these buttons was made? At least based from the shape? :confused:

Thank you.