The effects of Zn and Si on the hardness, tarnish 
resistance and microstructures of experimental Ag-
Cu-Zn-Si alloy were investigated by means of vick
ers hardness, tarnish testing, optical and scanning 
electron microscopy (SEM) and energy dispersive 
spectroscopy (EDS). The various compositions of 935 
sterling silver alloys produced by different casting 
techniques, investment (lost wax) process and metal 
mould casting, were compared. An induction casti
ng machine with a vacuum system was used for 
investment casting at 1,025°C with the mould temp
erature at 600°C whereas a LPG/oxygen single flame tip 
torch was used for the metal mould process. Vicker
s hardness of the samples produced via metal mould 
casting has higher hardness than that of the sampl
es obtained by investment casting. The hardness of 
standard 935Ag sterling samples produced by metal mould casting was around 66 HV while it was around 
56 HV for the investment cast samples. The increase in ha
rdness is related to differences in the cooling rate 
of solidification rather than to the addition of thir
d elements. The tarnish test was performed by immersing 
the samples in 0.1% Na
2
S solutions for 15-180 min. To specify th
e color change by ta
rnishing, the surface 
color differences (DE*) were measure
d according to the Commission Inte
rnational d’ Eclairage (CIELAB) 
standard. It was found that the tarnis
h resistance was improved with high a
dditions of elements especially Si. 
Furthermore, Si addition plays an important role 
in a complete microstructural modification, which 
coincides with the increase in tarnish resistance of st
erling silver alloys, in terms of transforming a lamellar 
eutectic structure to a predominan
tly Cu-Si continuous structure.