Thanks all for contributions.
I've found a picture that I like to share with the community. It's taken from Hodinkee Talking Watches and yes, the buckle is black...

Grazie Gianluca, se la trovi, sono sempre alla ricerca della corona senza logo!
Un caro saluto.
Daniele

: Hello Daniele,

: IMHO the buckle seems good to me, an original SUN one.

: Al the fakes ones I have seen so far have:

: a) the shield is in one piece with the buckle (the original ones
: have the Heuer shield as a separate part, then welded to the
: buckle);
: b) a longitudinal row in the back side of the pin (probably due to
: casting);
: c) being the fake ones in an alloy (maybe brass, not certainly
: stainless steel) the coating tends to wear prematurely leaving a
: matt finish.

: Cannot answer, instead, if originally the Monza had been released
: with a black PVD buckle, an unsigned one, or something else..

: My 2 cents.

: Best.

: Gianluca