adjective / noun
argent
AR-junt/ˈɑːrdʒənt/
Silver or silvery-white coloring, especially in heraldry.
A blue chevron crosses the shield's broad argent field.

Etymology
Latin argentum named silver, and English argent likewise served as a name for the metal. Its adjective use transfers the metal's appearance to the silvery-white color, including in heraldry.
In context
a kind of Silver Leaf was applied to those parts of the device that were Argent over time the silver content of these depictions has tarnished and darkened