Stirling silver or German silver

[rockelk]

I have recently been given a number of knives. Some have niello on them, some not. I feel safe to assume that the items with niello are somewhat equivalent to sterling even if they don't have a hallmark or numbers such as 925. However, two of the knives I question. Short of a destructive test I don't know of a technique to discern the difference. Attached are pictures of what I think are a Dha and a Qama. Are these tourist pieces or not? With Regards