The Colour of Diamonds

[Stevie Brazen]

Hi
I heard somewhere that Antique/Old Cut diamonds tend to be warmer colours than what is popular today, because that is what was being produced in South Africa at the time. Hence the term "Cape Diamond", for very warm antique diamonds (like that in my avatar). Ive tried to research this online, but have come up cold. Does anyone know, or able to reference the colour of diamonds over the last 150 years or so (other than the small blurb on the Brian Gavin site about Cape Diamonds)?

We know argyle pink diamonds are from Australia, but did South Africa produce mainly warm/yellow diamonds? If so, does South Africa produce white diamonds also? Where did the beautiful blue diamonds like the Shirley Temple and the Hope diamond come from? Legend has it that the Hope is from India, but that's highly questionable.

If you own a warm, cape or blue diamond, I would love to see your pics and hear the story or your stone.

 

[ChristineRose]

Here's a color chart...

https://www.ajediam.com/diamond_colors.html

White diamonds existed but most were cut into round brilliants. The capes were spared because the increase in sales value was too small to justify the risks of a recut.

The Smithsonian has this:

This diamond, which was most likely from the Kollur mine in Golconda, India, was somewhat triangular in shape and crudely cut.

I think that's pretty solid for a couple of reasons. The stone can be traced back to Jean Baptiste Tavernier, who was a merchant who traded in India. And it's possible to analyze the chemical composition of the stone with spectroscopy, which does not harm the stone. Every geographic area has a chemical footprint.

 

[OoohShiny]

Yoram / @diagem did a Blog article that might be of interest

http://gemconcepts.net/colorless-antique-diamonds-not-a-myth/

 

[Stevie Brazen]

Wow, thanks Christine and Shiny. Thats exactly the information I was looking for.

 

[AGBF]

I think there is some confusion in the writing, even by diagem, between a "white diamond" and a colorless diamond. The comparison between "yellowish" color stones and "white stones" sounds as if it is between lower (more yellow) and higher (whiter) color stones. Colorless stones, like the Golconda diamonds, are entirely different; they are type IIa. They are not whiter; they are colorless. They have a different composition from other diamonds. They can actually come in several different colors. "Regular" diamonds, which contain nitrogen in their crystal structure, can be very "white" (D color ones, for instance) while some colorless ones (Type IIa) diamonds may be brown!

Link...https://www.reenaahluwalia.com/blog/2013/7/8/type-iia-diamonds

AGBF

 

[Stevie Brazen]

Thanks AGBF. Type I and type II's add a whole other level of complexity to the study of diamonds. Just curious, how would one go about sourcing a type IIa diamond?

 

[AGBF]

Thanks AGBF. Type I and type II's add a whole other level of complexity to the study of diamonds. Just curious, how would one go about sourcing a type IIa diamond?

They are very rare and fetch a premium price. If I were looking for one I would have to be ready to shell out a huge amount of money for a stone. I would probably start asking on this forum for a reliable vendor who dealt in IIa stones. One can find vendors on the Internet, but I wouldn't trust just anyone to sell me a IIa stone. There are no more Golconda diamonds available at any price (unfortunately). I have always been fascinated by them.

I remember that one or two of of our professionals here on Pricescope came across Golconda-or at least type IIa-diamonds during their lives. They have posted about it. I wish I remembered who said he had handled them! Finding a colorless stone is extremely rare (outside of a museum). Unless you are Elizabeth Taylor and someone buys it for you!

Deb/AGBF

 

[foxinsox]

I think there is some confusion in the writing, even by diagem, between a "white diamond" and a colorless diamond. The comparison between "yellowish" color stones and "white stones" sounds as if it is between lower (more yellow) and higher (whiter) color stones. Colorless stones, like the Golconda diamonds, are entirely different; they are type IIa. They are not whiter; they are colorless. They have a different composition from other diamonds. They can actually come in several different colors. "Regular" diamonds, which contain nitrogen in their crystal structure, can be very "white" (D color ones, for instance) while some colorless ones (Type IIa) diamonds may be brown!

Link...https://www.reenaahluwalia.com/blog/2013/7/8/type-iia-diamonds

AGBF

that was a very enjoyable read, thank you! Also I had no idea Type IIas could be coloured!
There was a poster recently who was looking at buying or had just bought a Type IIa diamond and had the GIA paperwork to go with it

 

[AGBF]

that was a very enjoyable read, thank you! Also I had no idea Type IIas could be coloured!

Thank you for commenting. The Hope Diamond is a IIb. All diamonds are either a type I or a type II. The Hope Diamond has red-orange phosphorescence.

Deb

 

[OoohShiny]

I think there is some confusion in the writing, even by diagem, between a "white diamond" and a colorless diamond. The comparison between "yellowish" color stones and "white stones" sounds as if it is between lower (more yellow) and higher (whiter) color stones. Colorless stones, like the Golconda diamonds, are entirely different; they are type IIa. They are not whiter; they are colorless. They have a different composition from other diamonds. They can actually come in several different colors. "Regular" diamonds, which contain nitrogen in their crystal structure, can be very "white" (D color ones, for instance) while some colorless ones (Type IIa) diamonds may be brown!

Link...https://www.reenaahluwalia.com/blog/2013/7/8/type-iia-diamonds

AGBF

This makes my head hurt... lol

So IIa diamonds can have other elements (which give them colour) but will have very little / no Nitrogen in them?

 

[OoohShiny]

Link...https://www.reenaahluwalia.com/blog/2013/7/8/type-iia-diamonds

Ooh, I see that link references the Esperenza diamond! Someone should ask that blog author to link to the thread on here

 

[ChristineRose]

Here's my sorta explanation...

Think of a pyramid of oranges (carbon atoms) like you see at the grocery store. These oranges are covered with a sticky wax (electrical bonds) though, so they can shift around a little without falling over.

White light is light of all colors. Colored lights have different wavelengths. Different sizes of waves are either caught or pass through different gaps.

If you add some marbles (nitrogen) to the orange pile, the whole pile shifts towards the yellow. If the marbles are just the right size, they also make the crystal grow faster and be more stable because there's more room for a random orange floating by to get nudged the right direction. Or you can add pairs of marbles, and this time the spacing of the pile lets white light pass through. Or you can add little clumps of marbles. Or you can throw in some marbles at random and get brown diamonds.

So go back to the no-marble pile of sticky oranges. You could pack the oranges into a crate, and push against the sides (HPHT color) until the whole thing tilts sideways. No marbles, but you've changed the size of the gaps, and effectively changed the color.

Or, if the orange pile (no marbles) is an ugly color, you can push it back to white (also HPHT). This is standard for synthetic diamonds, but is less often done for mined diamonds because mined diamonds have more structural variation and are more likely to break so the process is not done on diamonds nice enough to be sold as is, and not-so-nice diamonds will likely break anyhow. You almost never see these for sale, and they aren't really bargains.

 

[AGBF]

Here's my sorta explanation...

Think of a pyramid of oranges (carbon atoms) like you see at the grocery store. These oranges are covered with a sticky wax (electrical bonds) though, so they can shift around a little without falling over.

White light is light of all colors. Colored lights have different wavelengths. Different sizes of waves are either caught or pass through different gaps.

If you add some marbles (nitrogen) to the orange pile, the whole pile shifts towards the yellow. If the marbles are just the right size, they also make the crystal grow faster and be more stable because there's more room for a random orange floating by to get nudged the right direction. Or you can add pairs of marbles, and this time the spacing of the pile lets white light pass through. Or you can add little clumps of marbles. Or you can throw in some marbles at random and get brown diamonds.

So go back to the no-marble pile of sticky oranges. You could pack the oranges into a crate, and push against the sides (HPHT color) until the whole thing tilts sideways. No marbles, but you've changed the size of the gaps, and effectively changed the color.

Or, if the orange pile (no marbles) is an ugly color, you can push it back to white (also HPHT). This is standard for synthetic diamonds, but is less often done for mined diamonds because mined diamonds have more structural variation and are more likely to break so the process is not done on diamonds nice enough to be sold as is, and not-so-nice diamonds will likely break anyhow. You almost never see these for sale, and they aren't really bargains.

ChristineRose, with all due respect, I am not exactly sure what you are explaining here.

AGBF

 

[AGBF]

This link is the absolute best one I know of for explaining all the ins and outs of Type I and Type II diamonds. One of our Pricescope regulars, kenny, has a collection of fancy colored diamonds. It doesn't really relate to this thread except that I thought (and I may be wrong about this) that the person who put up this informative website is also the vendor who sold kenny some of his fancy colored diamonds.

AGBF

Link...https://www.leibish.com/type-i-and-type-ii-diamonds-article-340