I had to learn the hard way about color-matching bulbs. My post above describes measuring the light color using a do-it-yourself colorimeter. Based on that measurement and on the words “warm white” from the Hue product description, I bought some 9w LED bulbs with the label warm white and 3000K color temperature. I put them in the ceiling fan fixture beside the indicator bulb. Drum roll, please. I turned on the light switch.
Disappointment! It still didn’t match. In fact, it looked just like it had with the original ceiling fan bulbs. Could it be that those original bulbs were 3000K bulbs? With all this swapping of bulbs, I decided to look closely at one. Below is a picture of the original bulb from my ceiling fan. It has a label just above the threaded base. That label includes the color temperature, circled in green.
I also looked closely at my Hue indicator bulb. It has a similar label, which again includes the color temperature. The photo below shows that the Hue bulb color temperature is 2700K. No wonder the color didn’t match with my ceiling fan bulbs!
I looked around my house and found that all the LED bulbs have labels just above the threaded base. I found two that are labeled 2700K and installed them beside the indicator bulb. While not a perfect match if you scrutinize the light output, it is good enough for casual inspection. Success! Now I can finally use my Hue bulb as an indicator per the original plan.
The moral of this story is to read instead of trying to figure it out. If anyone else installs indicator bulbs, they can go straight to the correct bulb type by looking at the labels. The DIY colorimeter results were not sufficiently precise for purchasing light bulbs, not to mention that setting up such measurements is extra work. Playing with the technology was sort of fun for me, but the rest of you can avoid my learning curve.