Desktop lamp / light


I would like to please get different perspectives / thoughts on the desktop lamp that the community has found the to be a quite versatile “general use” light source. e.g. While I am fortunate in that it takes only a moment to go outside to look at a diamond in literally “daylight conditions” it would be nice to look at the diamond and then a ruby [I am picking ruby deliberately, give, as I understand it a gemstone that requires exacting controls to accurately view] either of which may be set in X precious metal. Or it may be an all metal [metal alloy] piece of jewelry. All form a work desk.
To be able to set the light temperature is I think nice.

I did search for this topic but [admittedly do not have the best search skills] did not find a threat on this topic.So, sorry if the topic already exists.

Thank you,


You can see an example of an incandescent lamp and a fluorescent one together with their spectrum on wikipedia: Color rendering index - Wikipedia
This reference is pretty technical and mathematical…if you can follow it, it’s a great reference.

In general, daylight bulbs emit the full sunlight spectrum with a temperature of 5 - 6.5 degrees Kelvin…full sun does include UV…flourescent daylight bulbs have emission spectra that have spikes, LED’s are more uniform but still aren’t a flat spectrum. The intensity of the light also matters. No bulb can match outdoor full sun… you would have to search different daylight products and their spectra and output in Lux, rather than Lumens to find one that best matches your budget and needs. The bulbs themselves are not expensive. Going outside might be the best option for looking at an individual something closely… although impractical for viewing a lot of stones.

the wikipedia article is too technical for most people to understand. It does say that incandescent lighting has a broad spectrum… however, to achieve 6000K, a blue filter is used. There is more red and orange and lower frequency light in incandescents that don’t get hot enough to reach 6000K…I’ve actually had some experience with adjusted 5000K blue filter incandescents and using the Farsnworth Munsell hundred hue color sorting test for color blindness…it distinguishes 3 patterns of color blindness, one of which indicates optic nerve damage… I myself had taken a standard color blind test which indicated that I had some red- green color loss… the more accurate test under simulated daylight found that I just had some minimal poor color discrimination… The blue filter severely cuts down on the light intensity. Using high output incandescents like 500 watt halogen bulbs causes too much heat. the bottom line is to chose a bulb that most closely resembles daylight and has a high intensity when you search for daylight bulbs… a search will bring up hundreds of products… good luck on finding what you need.

Hello Steven,

Thank you so much for your reply and the link / information. Yes, this matter of choosing a table light that is versatile enough is a difficult one. It reminds me of the relationship between Sensitivity and Specificity of a test.

The whole topic of the lighting conditions effect on what you see is a fascinating one that also includes the physiology of how the eyes perceive color. So while one can choose a light environment that has objective measurable parameters the physiologic part seems more of an uncontrolled variable - I plan to learn more about this but my very very basic understanding is that the rods and or cones are not constant in their color perceptive functioning. So it would seem that there is a person to person variation and a circadian factor to.

I will look over the link you mention and see how far I can get with it.

But having said, part of the challenge is that there are simply so many lighting choices. Another route might be to simply patriot what a gemstone grading and or / choosing / sorting concern does.

Yet another sub part is the photography of the gemstone / jewelry. A goal in this would be to standardize the lighting conditions under which the photos are taken and then state these with the presentation of the image and or video.

Thank you,


Tricolor vision has it’s limitations… the brain has to synthesize what is basically digital data from light receptors firing and integrate it into perception. The first level of integration occurs within the retina itself, which in itself is an extension of the brain. My experience with color vision was neuropthalmology… it was clinical… color blindness patterns, protan, deutan, and tritan give information about retinal and optic nerve function… no one bothers with these tests anymore as they are too time consuming and routine ordinary testing of visual function suffices very well…The physiologic part is multivariate but can be controlled to some extent.
Finding the right bulb will be a chore… good luck and best wishes.

Now, this is a very good question!

What please is the exact question you are indicating?

“I would like to please get different perspectives / thoughts on the desktop lamp that the community has found the to be a quite versatile “general use” light source”
I’m still looking for the ideal desktop lightning after 32 years in the trade!

Your question is an excellent question indeed. And if anybody comes with an answer, it will be a great day for a lot of people!

Thank you. Thank you for clarifying. Your response is, from my perspective, a “proxy” answer to the question. I would like to suggest that we change the framing a little by use of the word “standard” instead of “ideal”. And to keep the “flow” of this thread some what “standardized” [ but not to constrain it to much]. Thus:

Given the wealth of experience that you - this community has- what lamp have you found that allows you to view a diamond or a ruby in a controlled standardized way? e.g. this X lamp does a good job of producing a lighting consistent with a day light [Y Kelvin temp.] for viewing diamonds.

Thoughts ?

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I agree outdoor sun is the best and I dont know anyone that can’t access that. But I’m glad I can still find incandescent bulbs still because i really don’t like LED at all.

be aware of the heat that high intensity incandescents generate. Halogens at 500 watts put out enough heat to catch things of fire if close to the bulb… They also do not completely replicate sunlight, as the temperature is at 4500K and not 6000K… as such, they won’t give off hazardous UV, but also will have more yellow in the spectrum than 5500 to 6000K which is sunlight…Xenon arc lamps most closely match sunlight so they could be a consideration, except for UV emission which is strong.

I mean incandescent that were around forever not halogen. Halogen get so hot they could start a fire.

regular old fashioned incandescents! good luck on finding one … have to order them on line or getting them at a specialty lighting store… best of wishes…

That’s what I meant. I buy on line and stock up!


Thank you all for your contributions to this tread. Maybe it is now time to move to the “brass tacks” [a US saying that means concrete,solid, the reality,the to do, the choice] phase.

So in an [goes without saying, that I am none the less saying] imperfect world, what is your best brand / model choice given the work you mostly do ? Please kindly indicate, generally [ or in detail if you would like] the nature of the work that you do and why the choice you have made works the best.

Thank you.

very good light for color accuracy

Hello Bear,

Looks quite nice and the price- wow - to say their pricing is “competitive” is an understatement; oxymoron like.

Thank you,