No brilliance involved, and I didn't invent it; this sort of comparator is commonly used in various industries. They are largely being replaced by electronic versions, but it's just too expensive to have that sort built for our application - minimum order is 5000 units.
Our version will use a box and vials from Hach Chemical, which is only 10 miles from my home. Since this a unique use for this device, obviously no standard color wheels are available. I will be fabricating this component, which will contain specific filters for the comparisons we need. It may be some time before the official color standard is released; this will be determined by Dr. Lebot, and will apply internationally.
In the meantime, I'll be attempting to get a "semi-official" standard approved. This will contain a wider "unknown" range than the final version, but should still be quite useful. The unit will be upgradeable, requiring only replacement of the color wheel to apply the official standard when it it released.