Sorry, here is why it was called the Golden Compass:
Philip Pullman: "The trilogy known as HIS DARK MATERIALS didn't have that name in my mind from the start. In fact it didn't have a name at all; it was just 'the big book'. When I'd finished the first volume and was talking about it with David Fickling, my British publisher, we tried various names and couldn't find one that worked. I knew that the trilogy needed a name, and that each of the books needed its own separate name too (I don't like numbers in titles: THE GODFATHER PART TWO, and so on. Just a fad. But it's my fad). So: what should they be called?
My first discovery was the phrase THE GOLDEN COMPASSES (plural, note). This comes in Milton's Paradise Lost, a poem which inspired me a great deal. The line refers to the Son of God taking 'the golden compasses, prepared / In God's eternal store, to circumscribe / The universe, and all created things."
In other words, these were compasses to draw a circle with, not a compass to find your way with. I liked the phrase, and the trilogy became temporarily, during the publication process, The Goldem Compasses. And we finally settled on Northern Lights for the title of the first book.
Meanwhile, in the US, it was being read by the editors at Alfred A. Knopf. Someone decided (mistakenly, but firmly) that the title referred to Lyra's alethiometer, which could be regarded as a sort of golden compass, but of the direction-finding and not circle-drawing sort. So the same someone or another someone decided to refer to the first book, for their own internal discussing-a-forthcoming-book purposes, as THe GOLDEN COMPASS.
Meanwhile, back in the UK, I had found the much better phrase, HIS DARK MATERIALS, for the title of the trilogy. I quote the passage from which it comes at the very beginning of the first book. Better, because it's more atmospheric, and there's the uncanny resemblance to 'dark matter', which figures largely in the story. So out went THE GOLDEN COMPASSES, and in came HIS DARK MATERIALS.
Meanwhile, back in the USA, the publishers had become so attached to THE GOLDEN COMPASS that nothing I could say could persuade them to call the book NORTHERN LIGHTS. Their obduracy in this matter was accompanied by such generosity in the matter of royalty advances, flattery, promises of publicity, etc, that I thought it would be churlish to deny them this small pleasure.
So that's it. The fact that all three titles refer to an artifact is no more than a coincidence, though it does make a nice pattern. Before I'd finished the third one, the artist Eric Rohmann, who drew the wonderful covers the books had in their first Knopf editions, asked what the third book would be called, and before I could tell him, volunteered THE SOPHISTICATED MONKEY-WRENCH.
One tiny final thing: my first suggestion for the third book was THE LACQUER SPY-GLASS. My editor at Knopf, Joan Slattery, pointed out that this might be mis-heard as LACK OF, and that made sense to me; so it became AMBER instead."