To be honest, it's a bit of a hit and miss job when I do these things! However, on a basic level, the basic recipe is something along these lines:
Base: Scorched Brown/Dwarf Bronze mix (1:1)
Redo the original mix
Thin PURPLE wash
1st Highlight: Dwarf bronze
and then keep on going up steadily with added bits of a silver colour (mithril silver will do the job)
However, the key to keeping everything together is bunging in thin purple washes after every stage (balances things out nicely
For the effects (and this *is* the hit and miss bit) - mix up some turquoise colour, and thin it a lot and simply splash it over in various places (recesses' mainly, but can go elsewhere). Add a touch of white into the mix to give small amounts of highlights to it if you want.
And then just tidy up - bit of bronze over some of the turquoise areas to balance things out.
That's about it I think, but honestly I'm sure the more technically abled could do this much easier than I do