It should be virtually the same as mixing colors. Blue and red highlight should give you a shade of purple. It may not look the same as a "color mix" but it may look purple in the right light.
The only way to know for sure is to try it. Use 4 oz plastic with one or two drops of black as your base. The smoke color will give you a background so the highlight can be easily seen. You will have to play with combination of the two colors.(how much of each such as 1 to 1, or 1 to 2 ,etc,) Be sure to keep track of what you do with pen and paper as you do it.
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