Steve, you can achieve your requirement either by using custom code, or by using expression for the pointer appearance.
Solution with expressions:
Simple State Custom GaugeTake a look at the Pointers -> Appearance tab. The Fill Style of the pointer is specified with the following expression:
=IF(TONUM(Params!GaugeValue.STR) =0, "#868689", IF(TONUM(Params!GaugeValue.STR) <=20, "#E32119", IF(TONUM(Params!GaugeValue.STR) <=40, "#F08A00", IF(TONUM(Params!GaugeValue.STR) <=60, "#FDC844", IF(TONUM(Params!GaugeValue.STR) <=80, "#89BA17", "#007770")))))
Hopefully this helps.
Best Regards,
Nevron Support Team