AP Strip Yielding Interesting Finding - Suggestions Appreciated

[Crank]

Ive recently come into posession of a bunch of gold plated mil-spec hardware. Ive attached a picture of a before and after AP strip.
I am finding that a soak in AP solution is releasing the gold plating from the metal perfectly. The odd thing is the "sheets" of gold have a silver colored underside. I found that these part are built to a specific that can use nickel as a way to adhear the gold. A quick google tells me that nickel is magnetic. If I drop a strong magnet into the flakes of gold, nothing sticks.
I'm now not certain what the "silver" is or if/how I should remove it (see picture). Do you guys have any suggestions of things I can do to better understand what I'm dealing with?

 

[FrugalRefiner]

The nickel is plated onto the copper before the gold is plated on top. It doesn't help the gold to adhere to the copper, it keeps the gold and copper from migrating into each other. If gold is plated directly onto copper, over time the two migrate into each other, and the gold plating starts to lose its effectiveness. This phenomenon happens even at room temperature. It seems counterintuitive to think that two solid metals could blend together unless they were at the melting point, but it does happen. The nickel layer between the copper and gold prevents this.

When you dissolve the gold foils, the nickel will dissolve too, but when you precipitate the gold, the nickel will stay in solution.

Dave

 

[Crank]

Outstanding!
Thank you Dave. I will press on processing the rest of these parts. Fingers crossed I end up with a favorable yield!