I see it is possible to purchase many different color temperatures in light bulbs from 3500K (in the red spectrum) to 6500K (in blue spectrum) all the way to 10,000K and even 20,000K or higher.
All bulbs available for purchase however comes in specific ranges. For example, you will not find a bulb that produces light in 5400 Kelvin or exactly 5200 Kelvin and so on. In other words, while there are many ranges available they are still limited to certain numbers.
My question is - how is the color temperature determined? In other words, does a given material always produce the same color temperature? Or is it possible to tweak a substance to produce any color desired? If yes, how would this be done?
FYI, I am interested in producing specific temperatures for a scientific experiment.