I went a little overkill and bought a Quazar Science Bi color tube. They have some of the most accurate LED color in the world at this time.
Other companies are doing good things, as well.
having a nice even spread can help too. hard shadows can hide defects and make the beans appear more visually busy. A 2 foot quasar tube can push light to either side of beans and you end up seeing more of the bean color instead of shadows.
i’d assume many of the home LED bulbs are getting better these days, so anything with good CRI or TLCI ratings tends to help a lot.
But we do so much based on the color of beans, a cheap LED can give your horrible visual feedback.
The traditional tungsten/incandescent lights were naturally color accurate, because it is heat generated, so it has a full spectrum color band, but is decidedly skewed warm. So it has less ultra violet, a little more blue, a little more green, and more yellow, and then a bunch of orange and red in a progressive almost linear increase. So it has a very even look despite being warm. This issue is that warm does skew the perception of how “yellow” a bean is. Today we have LED which is all made from dyes and pigments. So it might have an uneven color spectrum, which can appear “cool and white” but have serious dips in one of the color groups in the spectrum. And the warm LED can be almost montone in color having almost no blue spectrum.
Flourescent and LED both often have a green spike in their color spectrum. that is why old flourescent tubes often fave off they ugly green cast. LED does this more subtly, and is less a result of nature, and more because the manufacturer gets the color dye ratios wrong, or has issues making some of the colors more even.
We could just roast bu nose, but the nose gets fatigue pretty quickly, so i feel being able to trust your eyes is crucial too. In the past we never had to worry about the color accuracy of old filament bulbs because they were inherently color accurate. LED lights are a new industry challenge, but super crucial. In particular as influencers like Rob Hoos talk about how color is a major factor in flavor. So anything that throws the eye off is just throwing you even further off.
If you want to play around with visuals, you could also get an RGB tube or bulb from Philips Hue or Aputure, they tend to be accurate overall, but it allows you to play around with extreme colors via a phone app. You can check your beans under pure red, purple, blue, green etc. It tends to be a great visual tool. Good for inspection fun. But at the end of the day, having something repeatable and consistent by the roaster will be most important. So I might not have an RGB light there for fear i lose consistency by accidentally changing a setting on the light. I do however like having something bi-color to sort of adapt to the light coming in from outside. I find our eyes adapt to ambient conditions of light, so i like being able to slightly match the room a little warmer or cooler. but not having the option to skew green or magenta, or effecting saturation or all those crazy options. Just having a simple way to consistently and accurately dial warm or cool based on the time of day or weather outside.
Hope this helps!