It is with great sadness I'd like to announce Dr. Hanneman passed away on December 12, 2020. His legacy will live on forever!
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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Fri May 12, 2017 4:53 am 
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A mirror might help, but an auto bulb and resistor seems a better option, more light, variable colour temperature, repeatable results and much better fire safety.


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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Fri May 12, 2017 5:02 am 
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When alexandrite was first discovered all that was available was gas-light i think, so the effect was very pronounced in flame, then daylight. U are right about the 12v bulb & safety but the good effect comes from a candlelight, my experience-good responce- =D> 8)


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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Fri May 12, 2017 10:54 am 
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The reason candlelight gives a good effect is because of its low colour temperature. Putting an auto bulb in circuit with a variable resistor allows you to duplicate that low colour temperature, repeatably and safely.


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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Mon Oct 16, 2017 1:33 pm 
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Any LED flashlight with a warm temperature (3200 degree Calvin) will duplicate candlelight but with much more intensity.

Ebay has one called a Tank007 Jade Expert. It's cheap and effective.

For a hot light (Sun) seek out an LED with a hot temperature (6000-6500 degree Calvin).

I have one of each and hold both at the same time, simply move my stone from one to the next and back. Quite easy to evaluate color change stones this way.


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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Mon Oct 16, 2017 2:07 pm 
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I wold have thought 2700 degrees Kelvin would have duplicated candlelight more accurately, which is why I recommend a filament auto bulb and a rheostat, but that quibble aside the use of two colour temperature sources and alternately moving between them is good.
Interestingly, in emotional terms, redder lights (lower colour temperature) are referred to as "warm" colours, while bluer lights (higher colour temperature) are referred to as "cold" colours, even though the temperatures that produce the respective lights are reversed.


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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Mon Oct 16, 2017 7:37 pm 
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Alan F. wrote:
I wold have thought 2700 degrees Kelvin would have duplicated candlelight more accurately, which is why I recommend a filament auto bulb and a rheostat, but that quibble aside the use of two colour temperature sources and alternately moving between them is good.
Interestingly, in emotional terms, redder lights (lower colour temperature) are referred to as "warm" colours, while bluer lights (higher colour temperature) are referred to as "cold" colours, even though the temperatures that produce the respective lights are reversed.


Alan, I believe you are exactly right on that. The 3200 degree would be more incandescent temp. Thanks


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 Post subject: Re: Producing adequate "candle" light to capture color chang
PostPosted: Tue Oct 17, 2017 3:43 pm 
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Robin Winter wrote:
Is that practical if I want to photograph a piece of jewellery once I've set all the stones? I've seen a picture of the filter and the window doesn't look all that big on it.

Hold the filter next to your eye or camera.


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