While doing my research on Japanese CFL lamp color temperatures, I have noticed that low wattage CFL lamps are rarely available in 4200K and 3500K CCTs if they are magnetically ballasted lamps or self ballasted CFL lamps. Why is this so? I usually see low wattage magnetically ballasted non integrated CFL lamps as typically being available in 3000K, 5000K, and 6700K CCTs.

The early CFL's were expensive to make and not that mass produced, not justifying the wider color tone offerings. So only the warm white (2700 or 3000K), the daylight 5000/5500K and for the east markets (where the very high CCT was or maybe even still is seen as a kind of noble luxury) the really cold 6500..7000K. That means 3 color tones, quite enough for (at that time) non mainstream product...