I'd like to know more about the BACK of the pin, not the pinbacks. Some are silver colored -- others gold or even black. Some are smooth, others have lines or designs on them. Could a "fake" have the nice looking front pin design(as pictured on pinpics) and be made of a different metal?
Some of the pins on Pin Pics list the finish of the pins, which as you have stated varies. There is no one finish that is "official".
Many of the
Disney Store Millenium Pins have black/dark silver backs with texture. I have gold backed pins, black, silver and the black/ dark silver finished pins in my collection. They have come from
Disneyland, Walt Disney World, Walt Disney Imagineering (WDI), Japan DS, UK DS, USA DS, Disney Auctions, DisneyShopping, Disneyland Paris and EuroDisney. I do have some Bertoni pins (made in Italy) which have very black backs and are a heavy metal, to some plastic like pins from the UK.
Pins from Europe and Japan have a whole different range of finishes both front and back.
Newer pins (2003 and on??) from the USA have the Pin Trading Logo.
Best bet is to look it up on Pin Pics, if it doesn't specify and you really want to know, you might try posting here or on Dizpins BB and ask if anyone has the pin. You can compare backs and find out that way. Compare the Copyright mark listed on the pin on Pin Pics with the one on the back of the pin. That is really the only sure way to tell if the pin is legit.
Hope that helps a little.