? be possible. VerdiCare
is not normally available in Australia ,but it may be importing some from the 'States.
A tiny droplet over the spot only
may help to improve the appearance, for wayyyy less than $50 .
NZ Halfcrowns of this date are only 50 % silver.
I have seen good results pictured here in the CCF, on coins of similar alloy:
(50% Ag, 40% Cu 5%, 5% Ni, 5% Zn, - otherwise known as 'Quaternary Metal.),
the alloy used for .500 fine silver coins throughout the British Empire 1922-1946.
How can Australian collectors purchase VerdiCare
? - I could use some myself.