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bcmacdonald

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2021-08-everybody-loves-the-blues-1024x573.jpg


John Pollard published a new blog post.

Feelin' Blue


The Blues genre is a cyclic musical form characterized by a 7-note heptatonic scale, swing rhythm, a walking bass line, and "call and response" using specific harmonic progressions....

Continue reading the Original Blog Post.
 
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Garry H (Cut Nut)

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Great fun expose Sir John,
I have a trick when people send me enhanced images like all those. I ask them to place the gem ontop of a phone with the image on the screen and then send me a photo of the photo and the gem.
This is about what I usually get and about as good a blue as I have ever seen
1628572372946.png
 

John Pollard

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Great fun expose Sir John,
I have a trick when people send me enhanced images like all those. I ask them to place the gem ontop of a phone with the image on the screen and then send me a photo of the photo and the gem.
This is about what I usually get and about as good a blue as I have ever seen
1628572372946.png

Thank you @Garry. Your point is a nice opp for context - and compliments.

Context

Christie's and Sotheby's (you reproduced their photo, above) were making enhanced glamour shots like this before photos were ever used to sell diamonds on the internet. They do it to generate buzz. They also take the position that no photo can do such unique diamonds justice.

Your point should surely be kept in mind for people buying FCDs - photos are often enhanced. In terms of Christie's and Sotheby's auctions, the subject items make a tour of cities like NY, Dubai, HK, etc., so that multi-millionaire and billionaire-bidders can send their own representatives to examine the specimen in person and provide them with a comprehensive and accurate description. Mark Cuban can be an impulsive guy, but I wager the chance that maverick would instinct-bid on a $40 million colored stone without seeing it - or having inside information from a trusted agent - is pretty low.

Once purchased by a collector, such items - set in jewelry - are usually staged in a display case in a low lit room with discrete, carefully placed LEDs "environmentally enhancing" the stone to optimal effect.

Compliments

This strikes me as an opportunity to extend compliments, a tip of the hat, and thanks, to PriceScope's vetted vendors, who have gone to such great effort and expense over the years to develop imaging and systems which carefully and accurately represent the color and clarity particulars of diamonds they're offering for sale.

Finally, for any PriceScoper who's considering to bid $40-60 million (or more) on the finished blue that comes out of Petra's 39 carat rough in the article... Keep Garry's post in mind.
 

John Pollard

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Blue diamonds look perfect and stunning, aside from its one of my favorite colors. It entails faith and trust. How wonderful it is!

Very true. It has always been my favorite color.
 

oncrutchesrightnow

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Is there a reason cutters make flawless diamonds out of these things? They are so rare, it seems wasteful. Don’t you think most people would settle for SI1? Think about how the number of human eyeballs enjoying the number of blue diamonds spending time glittering in the sun would increase. Such a shame to insist on perfection for one stone and then leave it in a box. Just a philosophical question. But as the article says, what makes the diamond blue is the human eye missing red. Logic dictates cutters ought to cut for maximum blue-sparkle-perceived, which means a blue diamond for each of us, right? Think of the betterment of humanity.
 

Wink

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Logic dictates cutters ought to cut for maximum blue-sparkle-perceived, which means a blue diamond for each of us, right?

I believe this is the sentence that leads to your comment: "This causes a defect in crystal structure which changes light transmission, selectively absorbing visible red light while selectively transmitting visible blue light, so when light passing through the diamond reaches the human eye the observer sees blue."

I have bolded what I think is the important part of the sentence. It is the crystal structure of the diamond that is causing the light to appear blue, not the cutting.

I sincerely wish it was possible to tweak cutting to make a diamond appear blue. I would be wearing two or three myself if it were possible.
 

Garry H (Cut Nut)

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Yup, cutting can increase the overall fire but not the specific colors.
And BTW wink - absorption of yellow causes the blue color.
We shone a UV light on an Argyle blue yesterday and it had weak yellow fluorescence. Not a positive if it were strong as it would weaken the blue tone.
Argyle blues are not caused by boron.
Side fact - many boron blues fluoresce and phosphorous a really nice red.
 

oncrutchesrightnow

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@Garry H (Cut Nut) Hm, that’s interesting about yellow v. red light absorption. Must be different than the article.

@Wink, totally get that, I meant cutters should go for smaller, more included diamonds so the rest of us could get some. :)
 

Wink

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And BTW wink - absorption of yellow causes the blue color.

You will have to take that up with the author of the post I was quoting. I find him to be very excellent in his material, so it will be interesting what he has to back up his side of the story with...
 

John Pollard

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Blue fluoro in diamonds washes out yellow.
Yellow washes out blue.
It is color 101 Wink.
I will alert Sir John.
Hi @Garry H (Cut Nut)

Science shorthand: Light closer to infrared WLs (including yellow) is from the "red portion" of visible spectrum, as opposed to light closer to ultraviolet (includes indigo/violet).

1628893129739.png

I edited the post to stipulate "portion." - Thank you for the keen eye.

<< This causes a defect in crystal structure which changes light transmission, selectively absorbing light in the red portion of the visible spectrum, while selectively transmitting light in the blue portion of that spectrum, so when light passing through the diamond reaches the human eye the observer sees blue. >>
 

John Pollard

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Is there a reason cutters make flawless diamonds out of these things? They are so rare, it seems wasteful. Don’t you think most people would settle for SI1? Think about how the number of human eyeballs enjoying the number of blue diamonds spending time glittering in the sun would increase. Such a shame to insist on perfection for one stone and then leave it in a box. Just a philosophical question. But as the article says, what makes the diamond blue is the human eye missing red. Logic dictates cutters ought to cut for maximum blue-sparkle-perceived, which means a blue diamond for each of us, right? Think of the betterment of humanity.

@oncrutchesrightnow , as a lover of the unique, I sometimes wish they would choose to leave such rough as-is. I wager that's unlikely as long as we see whomever buys, polishes and auctions it earning far beyond what the original rough sold for.

In terms of the FL question, cutting decisions may be driven by cleavage planes, crystal structure, etc., as much as achieving a certain clarity grade. For sure, the producer will likely want the highest clarity practical, but maximizing as much raw material as possible in the final stone is paramount for specimens like these.

A good example of maximizing material would be the planning of those historic Argyle pinks, which were frequently produced in low clarities. The unique coloration of pink and red diamonds is caused by distortions in the crystal lattice resulting from intense heat and pressure during their formation. That frequently makes them tricky to plan and cut. Here's a related story that might interest you, penned by my favorite Italian gemologist:

The big pink disappointment
 

Garry H (Cut Nut)

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@oncrutchesrightnow , as a lover of the unique, I sometimes wish they would choose to leave such rough as-is. I wager that's unlikely as long as we see whomever buys, polishes and auctions it earning far beyond what the original rough sold for.

In terms of the FL question, cutting decisions may be driven by cleavage planes, crystal structure, etc., as much as achieving a certain clarity grade. For sure, the producer will likely want the highest clarity practical, but maximizing as much raw material as possible in the final stone is paramount for specimens like these.

A good example of maximizing material would be the planning of those historic Argyle pinks, which were frequently produced in low clarities. The unique coloration of pink and red diamonds is caused by distortions in the crystal lattice resulting from intense heat and pressure during their formation. That frequently makes them tricky to plan and cut. Here's a related story that might interest you, penned by my favorite Italian gemologist:

The big pink disappointment

The leftover preformed un sawn diamond is here in Melbourne at our local museum. Rio donated it. Anyone can visit it. The problem was not the skilled cutters - it was the unskilled cutters. They should have sent it to LTM or some other specialists who would have performed all the work under water or coolant.
The cutters at Argyle have created bilions of dollars of waste - so many pinks they polished in Perth were bought and repolished to improve the color. The cutters had colorless experiance, a cushy job, and no market forces or competition.
The stress in almost all Argyle diamonds is a result of their rough ride to the surface resulting in much of the crystals dissolving and shrinking (which is why the average carat weight was around 0.10ct). Created lovely trigons and patterns though on the rough surfaces.
Ellendale, several hunderd miles to the west, also came ub thanks to Lamproite.

Little know fact - diamonds do not form in kimberlite or lamproite - they are just deep seated enough volcanoes to have been able to pass through a diamond growth region and bring the little suckers up to the surface. They need to come up really fast - 50-100mph - or otherwise you get the Argyle effect, or no diamonds at all - just methane and CO2.
 

Garry H (Cut Nut)

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Compare the real color in this image from the museum, to Johns IGI article. That's what I am talking about. Having seen it on a tour by the museum director and with Ewen Tyler who found the mine, I can assure you, the museum photo is the real deal.
1628910619336.png
1628910654934.png

Anyone notice the laser marking to guide the polishing planes?
 

John Pollard

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The leftover preformed un sawn diamond is here in Melbourne at our local museum. Rio donated it. Anyone can visit it. The problem was not the skilled cutters - it was the unskilled cutters. They should have sent it to LTM or some other specialists who would have performed all the work under water or coolant.
The cutters at Argyle have created bilions of dollars of waste - so many pinks they polished in Perth were bought and repolished to improve the color. The cutters had colorless experiance, a cushy job, and no market forces or competition.
The stress in almost all Argyle diamonds is a result of their rough ride to the surface resulting in much of the crystals dissolving and shrinking (which is why the average carat weight was around 0.10ct). Created lovely trigons and patterns though on the rough surfaces.
Ellendale, several hunderd miles to the west, also came ub thanks to Lamproite.

Little know fact - diamonds do not form in kimberlite or lamproite - they are just deep seated enough volcanoes to have been able to pass through a diamond growth region and bring the little suckers up to the surface. They need to come up really fast - 50-100mph - or otherwise you get the Argyle effect, or no diamonds at all - just methane and CO2.

Fascinating stuff @Garry H (Cut Nut) .

Seeing your mention of Ellendale, do you have any inside info on this story?

 

Garry H (Cut Nut)

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Fascinating stuff @Garry H (Cut Nut) .

Seeing your mention of Ellendale, do you have any inside info on this story?


Yup, had lunch with Partick Stringer from India bore and introduced him to Ewen Tyler in May. first 'me Patrick on one of Branko's webinars about 9 months ago and we have communicated a lot since.
They and Blina have found paleo (ancient) channels covered with a few meters of sand. They found them using low tech aquifer electric current techniques - they lead away from the weathered lamproites to an ancient sea and therefore concentrated the diamoniferous channels over about 22 million years. Patrick intends to run a small low budget operation funded by the non yellows and build up an inventory and self brand the yellows. I hope to have some involvement.
 
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