Recently, and for the reason this thread was started, I have completely dismantled the front badge on my GTV.
Some of my findings may apply to the 147 etc.
I discovered that the body of the badge is a gold anodised aluminium alloy casting and forms the gold lip surrounding the outer blue Alfa Romeo ring on the GTV.
There is glued to this body a thin domed pressed alloy disc with the badge features slightly embossed (this is why we can get a 'silver' badge when the colour applied to it fades and is removed by the owner). This colourwork is fragile and is covered by a thin overlay of transparent material which if damaged lets the weather finish off what the Ultraviolet has already started.
The complexity of manufacture explains why OEM badges are Megabuxx!
I reckon that the Ebay Italian supplied stick-ons are much nearer to the originals not only in colour, which looks spot on, but also because they are metal backed and in the fitting instructions they seem to recommend that the embossed silver disc has to be removed before applying the badge.
Does anyone know if they are plastic over a metal backing 'cos it says it is "the same as the original" on Ebay?