the knob is made up of 2 parts

th inside - the slope bit with numbers
i think that this is a lambert with a file texture and bump
the texture has a yellowy orange/gold background

then there is the cyclinder that encases it
this is a mental ray node called dieletric (spelling)
what it means is that it reflects some light, lets some pass right through and lets some reflect inside the objcts so u get that effect of like diamonds
i changed the colour (col) to an orange/red u chose what ur ooking for
and changed the lor and lor_out settings
to get the look i was after
this will change how far u see into it ect