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James Catmur
Site Admin
Joined: 14 Sep 2006
Posts: 1476
Location: Cambridge
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 Posted: Jan 14, 2020 11:57 Post subject: Re: Display cabinets |
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Alfredo
Which might be why I ended up, through trial and error, going for LEDs within the case and halogens outside it (where heat is not an issue).
You have explained the decision I took year ago!
| alfredo wrote: | | I seem to have a lot of minerals with a green or blue-green color due to iron, for example ludlamite, boracite, and many others. Those minerals seem to look their best under daylight or halogen lights (which are the closest approximation to daylight of all the artificial light sources, as far as completeness of the spectrum goes). Unfortunately halogen lights put out a lot of heat, and so fell out of favor. But none of the other artificial light sources come close to duplicating halogen‘s spectrum, so my ludlamites and boracites look greyish and washed out. Greens due to chromium on the other hand look brilliant, so jewelers are happy with the way their emeralds look in the showcases. I guess showing emeralds at their best is commercially more important than showing ludlamite at its best, ha ha. But anyway, pay less attention to the "color temperature" of a light source, which basically only tells you how much blue is in the light and says nothing about how complete the spectrum is. I‘m patiently waiting for an LED that duplicates halogens or sunlight before investing a lot of money in deficient current light sources that will probably be outdated by new technology a year or two from now. |
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Jesse Fisher
Joined: 18 Mar 2009
Posts: 639
Location: San Francisco
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| Posted: Jan 14, 2020 13:02 Post subject: Re: Display cabinets |
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| The graphs that Roger posted point out what I was saying about LEDs - they do not produce a continuous spectrum. The appearance of some minerals are more sensitive to this than others. My feldspars and other silicates don't seem bothered, so I have installed a couple inexpensive LED strips in the case for them. Not a lot of money has been invested, so as the technology improves (and it will), I can happily replace them without sacrificing a large investment. For others such as the fluorites, I am sticking with halogen for the moment, as it gives the best color rendition. I only have 2-4 of the 20W 2-pin bulbs per case, so heat buildup has not been a problem. If one needs something brighter, I imagine that installing a small fan or blower to ventilate the case would be less expensive than investing in an expensive LED setup, which may well be obsolete within a few years. |
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Bob Morgan
Joined: 18 Jan 2018
Posts: 251
Location: Savannah, Georgia
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| Posted: Jan 14, 2020 23:17 Post subject: Re: Display cabinets |
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For those who will be in Tucson Feb. 3rd, the Mineral Society program will have a lighting expert as guest speaker. Dr. Anthony Gleckler's talk is titled "How Your Eyes, Lighting and Minerals All Interact".
I hope to see some of you there. |
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