German Silver and Nickel Silver are slightly different alloys of Copper, Nickel, and Zinc. The old German silver, in theory still made but I don't know who sells it, has more of a yellowish cast, the Nickel Silver available today is whiter.
The degree of whiteness comes mostly from the nickel content of the alloy, and to a lesser degree from the zinc.
Yeah, it is hard to matchold German Silver with what is commonly available today.
From a little unpublished work of mine, Gun Metals:
The most commonly available “German” silver alloy available today is called, variously, Nickel silver 65-18, or 18%—alloy A. The UNS number for this grade is C75200. Nominal chemistry is 65% copper, 18% nickel and 18% zinc. It has a silver-white color. The whiteness in nickel silver comes mostly from the nickel content, and to a lesser degree from zinc. I have observed that the alloy used on old American rifles has a more yellowish cast than seen with modern alloy.
There are many “nickel silver” alloys listed today. One current alloy which is actually tradenamed German silver, rather than Nickel silver, is 65% copper 12% nickel and 23% zinc. UNS C75700. Because of lower nickel, this grade may be expected to be somewhat less white in color than the 65-18 alloy. By comparison it appears yellowish. This matters when one attempts to repair an inlay on an old rifle, and exact color match becomes important.
The German silver trim on the sheath of this (my, not shown here) old Bowie knife, marked NON•XLL Joseph Allen & Sons, Sheffield is 61% copper 24% zinc 14% nickel, with assorted residuals. This metal has a yellowish cast, which is not matched by the new sheet of nickel silver in my shop.