PQ 14 planets look cold and icy, yet seem fairly livable for some reason.
PQ 15-17 are Earth-like with increasing size.
PQ 18 is strangely out-of-place, being all green and yellow, like some-sort of junle world.
PQ 19-20 are Earth-like again, increasing in size.
PQ 26 or better planets are those glowing purple huge ones. They are very rare naturally, but you'll probably make some yourself once you have Terraforming technology. They are Eden-like worlds with higher production values.
Gerakken was talking about purple *stars*, which apparrently also exist, but are also very rare. Purple stars have higher influence but not necessarily higher-quality planets.
Bruce