Change default (pre selected) color in color picker in custom theme, without changing order of colors displayed

[MalinS]

Hi, I have created custom themes before, but this time I would like to change the default (pre selected) color in the color picker, without changing order of colors displayed.
In the image (Classic theme) the six:th color is pre selected. Instead of the six:th I would like to set the first color as pre selected, but can not find a property in the theme.json for that purpose. Anyone?