RGB Technology can be tricky. When dealing with RGB technology, there are several key things that you need to be aware of to better understand it.

RGB technology on a black screen operates differently compared to RGB that does not have a black background to utilize. For example, on a visual screen like a TV or computer screen that is black. If you are trying to achieve a Maroon color. You would merely dim the RED down by half and the blackness of the screen would combine into the red to portray a MAROON color. Every color has different shades that can either be combined with a white background or a BLACK background. Trimlight systems and all Pixel type systems do not have the BLACK background to combine with the color to make every desired color that you would see on a computer screen or Television.  We have found a list of color codes for an RGB system to find select colors. Some of these colors will require the BLACK to get the desired effect, while others can be adjusted perfectly because they do not utilize the black as part of the color.
ONE MORE THING, To get to BLACK as a color. That would be merely turning off the lights completely. But since the Trimlight bulbs are White/Clear in color. You are unable to achieve black as a color option.
*** Trimlight does not state that all of these colors can be found on a Trimlight system but the list may help you to find a few on your system that may have been harder to find without this guide.