Spark Plug Base Color on 37 Dictator

[drdon]

Can someone tell me, for 1937 Studebaker Dictators:
1) is the color of the base of a spark plug an item examined during a national judging?
2) if so, is the base silver metal, or a black color as I have heard?
I have a 28 Harley with original plugs which are metal bases (unpainted) so I know that
older vehicles came without painted bases. Howeve, maybe in the later 30s, this
changed.
Any help out there?

[Spitfire8]

Blued metal was original. Plated plugs didn't arrive until the mid-1950s.