Fluorescent modelling light?

I am photographing some platinum bars for a precious metals company and need a 5600K bulb for my Visico Excel VC300. A constant light source is a necessity for the kind of shoot where you rely on getting the correct light reflection.

I'm currently using a 250w halogen bulb similar to this: http://www.amazon.co.uk/Longlife-Modelling-Elinchrom-KARLite-Elemental/dp/B009ZS5NE6/ref=sr_1_5?ie=UTF8&qid=1360331909&sr=8-5, but the yellow light discolours the metal. Is there a direct fluorescent replacement bulb which has no colour cast on even the lowest setting, and can there be any compatibility issues?

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