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 Post subject: color change sapphire
PostPosted: Mon Jun 22, 2020 6:16 pm 
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Hello

What degree of color change would you consider this sapphire to be?

https://www.youtube.com/watch?v=acRP6sg ... e=youtu.be

Im not really sure of the light sources I put them under, just my desk lamp and the room light.

Also, I head most color changes sapphires are unheated but this one is heated. is it true that most are unheated? Thanks

Armando P.


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 Post subject: Re: color change sapphire
PostPosted: Tue Jun 23, 2020 8:34 am 
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I think that the color change has nothing to do with the inclusions or if the stone is heated but with the chrome content. The sapphire has Boemite inclusions and is not heated. Let's hear what the pros have to say.


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 Post subject: Re: color change sapphire
PostPosted: Wed Jun 24, 2020 2:51 am 
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Those loook real nice. Love the pics


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 Post subject: Re: color change sapphire
PostPosted: Wed Jun 24, 2020 3:16 am 
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U got 4 colors in that one! I thought it was 2 stones at first. How did u get the red?


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 Post subject: Re: color change sapphire
PostPosted: Wed Jun 24, 2020 5:37 am 
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Thank you very much.

All 4 photos are of one stone. The first photo on the upper left was taken in daylight, the second photo on the upper right was taken with direct lighting with a Mini Maglite, the third photo on the lower left was taken with indirect lighting with a Mini Maglite and the fourth photo on the lower right was taken through a Chelsea filter. All pictures were taken with the camera of my mobile phone.


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 Post subject: Re: color change sapphire
PostPosted: Fri Jun 26, 2020 2:13 am 
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As for your original question I would say you have a subtle color shift sapphire. You have to understand that any material "changes" color based on the incoming light (which in turn is based on the wavelenghts it emits). If you look at your hand, you can see the skin is also "changing" in hue.
A True color change label is given to materials that react to different illumination in a much more extreme way. To such an extent actually that it messes with the human visual system (and its color constancy mechanism) and makes you think that the stone is say red, but then you light it with another illuminant and you are now convince it is green.

It gets quite complex, mostly because a lot of it has to do with the way we perceive light and how its process in the brain.

Hope that makes some sense.


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 Post subject: Re: color change sapphire
PostPosted: Fri Jun 26, 2020 2:59 am 
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I have found something else that explains the complicated process relatively simply.
Under daylight, or fluorescent equivalent light, the typical color change sapphire’s basic color ranges from blue to violet. Under incandescent light (electric light bulbs, or candle light), the color changes to a range of violetish purple to strongly reddish purple. This effect is caused by the interaction of the sapphire, which absorbs specific wavelengths of light, and the light-source, whose spectral output varies depending upon the illuminate. Traces of metal impurities in the sapphire, such as chromium and vanadium, are responsible for the color change. Source:https://www.thenaturalsapphirecompany.com/blog/color-change-bi-color-sapphires-the-chameleons-of-the-sapphire-world


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 Post subject: Re: color change sapphire
PostPosted: Sat Jun 27, 2020 2:35 am 
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Yes that makes sense. Ive never seen it before so it is interesting to notice. Blue to red would be cool


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 Post subject: Re: color change sapphire
PostPosted: Sat Jun 27, 2020 7:38 pm 
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chrisP, that is what is happening at a physical level, different illuminants have different wavelenght outputs. Materials have different absorption spectrums, and in some gems have several windows through the spectrum which end up biasing the color towards one or the other absorption peak depending on the illuminant. That part is mostly if not, completely understood. The other part, the psychology and physiology of what happens with those photos once they enter in your eye and subsequently interpreted by your brain, is when the waters get muddy sort of speaking.
There are a lot of metal processes (or shortcuts) our brain goes through in order to efficiently decode everything we perceived. One of them is "color constancy", you know an Orange or Apple are still and Orange or Apple at noon, overcast day, or bright red smokey sunset. A survival technique (you don't wanna confuse a juicy ripe red apple with a green tomato and get sick under reddish sunset lighting) and efficiency mechanism in order to structure and understand the world we perceive. Likewise to the untrain eye, you ask someone to tell you what color is a cloud and they will say "white". When clouds are a myriad of colors throughout the day.
Visual illusions poke at these processes shortcomings and expose their weaknesses. Like for example how the brain pushes Values up or down in brightness or Hues around the color wheel.
It is hard to unlearn or sometimes impossible to un-see what your brain has learn over a lifetime, but at least knowing the limitations can makes understand color better (color change Gemstones are like the illusions below, it gives us that sense of magic/awe we have lost long ago when we were kids)

The three color chips are the same Hue, the middle one is pushed by our brains towards orange, when it is actually brown
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A and B chips are the same Value. Constrast is accentuated because our brain knows the B chip is in shadow, and the A is in light.
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erase2.jpg [ 16.72 KiB | Viewed 1059 times ]


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