We call the color that Sim originally posted "Pro Blue" and we see it shot as a laminate like in Sim's pic or shot using a twin injector or blending block so the back and belly colors wash together a little where they meet. Either way, its a great color. Cold water walleyes hammer that color scheme. Personally I hand pour the bellies and them shoot the color over the top. I make the back color just like I suggested and I can get it darned close to whats show but up here we'll maybe see 15 different baits that are similar in shape and profile in Pro Blue and everyone is different in the shading of the back color.
The trouble with internet pic s and color matching is that every monitor sees colors differently. That can make accurate color duplication a challenge. On this pro blue though, I'd just start with something and slowly work up to having a color that I want. A great way to do this is to pour some of the belly color out on a piece of flat metal, the back of any mold will work great. Then as you start to draw that back color into something you can live with just pour a 1/2 teaspoon of it along side the belly color. When the back color is cool enough to handle lay each color on top of the other and take a walk outside to see how they look up close and personal. You'll know when you're there.
Don't hurry yourself. The old adage that haste makes waste is never more true than when working with this plastic. This color combination is a good one to practice with. Great topic here.