Do the chocolates vary in color as there seem to be quite an array of colors in there and the white sand makes them POP...
What are their tank sizes??
Heh, they're actually pretty dull in that tank, for whatever reason. I have culls (clear chocolates pulled from the tank in the photo) in with platy fry and some of them are completely opaque now. I have a bunch in a tank with bright white sand and corys and I have some solid black, brown, and red-wine colored in there. Neocaridina coloration is highly environment dependent. It seems to be a function of light, background / substrate color, and inhabitants. Neocaridina kept with creatures larger than themselves seem to color up more solidly.
The below photo is from my bright white sand / cory tank.
Chocolates are the basis of many of the various colors out there. Mine throw blue, opaque black and brown, carbon rili, and opaque wine red, among others. I have a very large solid wine red female in the same tank as the black one below. I'll try to grab a photo of her sometime (she doesn't seem to want to sit still every time I point a camera at her).
The tanks in the above photos are 10g. The below comes from a 20g tank.