There is always speculation that light intensity may result in intense color for hoya flowers. I am going to go out on a limb and say that maybe a factor in the coloring of some hoya flowers but there are always other factors that may also have a role in that theory. As I scroll through the many photos of hoya blooms that I have, it is obvious that most species bloom very different from time to time and color would not be a constant in identification. I will not pretend to draw conclusions to what alters the spectrum of color within a hoya species because there is no possible way to know for sure.
As I have grown outside under the intense Florida sunshine as well as under intense artificial lighting I notice there is not much change in the color of the flowers. Does that mean that the grow lights and inside conditions can be mimicked closely enough to take out the nature factor? Hoya obscura is one hoya that grows easily and blooms quite often under any conditions and you will notice the contrast in color of the cute fuzzy flowers. Each just as beautiful and unique as the other. The white flowers happened while growing 5 feet from a tinted west window in the middle of summer. The intense pink color is from a flowing cycle that happened growing outdoors under a screened lanai covering in the middle of summer. You decide which one you prefer. For me, it is always interesting to experience what the blooms will eventually mature into since noting is consistent in nature!