Mass of fine silver = (M(R - H))/(1000 - R)
This equation will give you the mass of fine silver required to
raise the Olympic coin silver to Sterling silver.
M = The weight of metal on hand (in grams)
H = The precious metal content of the metal on hand in parts per
R = The precious metal content of the required metal
Slot in your figures, and you should be good to go
and example of using the equation :-
Let’s say you have 10 grams of coin silver, and you want to know how
much fine silver you need to improve the precious metal content.
(10(925 - 625) / (1000 - 925) = 3000 / 75 = 40 grams of fine silver.
Regards Charles A.