There is nothing special about the choice of color. No brain and 20 intelligences.
If you really want to collect colorful stones,
The yellow one is this one.
Red can use glow amethyst,+12 method is strong+10 intelligence.
Blue can be an extraordinary zircon or an eternal eye.
You can also try the nightmare tears,+10 attribute.
Because nq at this stage is mainly to increase intelligence, others are second.