Pink diamond 'behaviour' solved but colour still a mystery

Jan 08, 2013 by Hope Holborow, Science Network Wa
“What we’ve seen is that the diamond colour—the amount of absorption that gives it the pink colour—is dependent on both the wavelength and intensity of the light”—Mr Byrne. Credit: Fancy Diamonds

UWA scientists have explained the photochromic behaviour of the pink diamond in an attempt to uncover why they possess their pink colouration.

Published in the journal, Diamond and Related Materials, the paper shows that the photochromic behaviour of the pink diamond can be explained by 'competing photoionization processes at multiple defect centres in response to an applied optical pump'.

Lead author and PhD student Keal Byrne says the team focused on why diamonds change colour under light.

"We have pumped these diamonds with various and measured the response in both time and absorption intensity," Mr Byrne says.

"What we've seen is that the diamond colour—the amount of absorption that gives it the pink colour—is dependent on both the wavelength and intensity of the light, and what that is consistent with is a model of between the unknown pink defect and other defects in the lattice," he says.

This research has shown the defect centres responsible for many diamond colours, do not explain how pink diamonds get their colour.

"Colouration in diamonds is due to crystalline defects in the , which are also known as colour centres as they induce colour," Mr Byrne says.

"The colour centre responsible for pink colouration is unknown."

The team investigated photochromism, modelling the pink diamond photochromic process as 'an optically-driven between two (or more) separate defect trap states, one of which acts as a ground state for the 390nm and 550nm absorption bands'.

The paper identifies that the pink coloration arises from 'absorption bands centred at 550nm and 390nm. The depth of these bands can be reduced (the diamond can be 'bleached') under ultraviolet illumination of the diamond and can be restored with longer-wavelength light'.

"Defects introduce transitions into this that absorb invisible frequencies," Mr Byrne says.

"So we're trying to work out what these new energy levels are that are unique to the pink diamond and by that way we can work out what properties it has and what use it might have."

Mr Byrne says he is still interested in furthering this research to discover why this pink colouration exists and where it comes from.

"I'm happy that we've managed to describe its behaviour, but some big questions still exist and hopefully we can answer them," he says.

Explore further: Physicists advance understanding of transition metal oxides used in electronics

Related Stories

New scientific research reveals diamonds aren't forever

Jul 18, 2011

(PhysOrg.com) -- In a paper published in the US journal Optical Materials Express this week, Macquarie University researchers show that even the earth's hardest naturally occurring material, the diamond, is not ...

Hope Diamond's phosphorescence key to fingerprinting

Jan 07, 2008

Shine a white light on the Hope Diamond and it will dazzle you with the brilliance of an amazing blue diamond. Shine an ultraviolet light on the Hope Diamond and the gem will glow red-orange for about five ...

Researchers discover secret of weevil diamond-like coat

Dec 22, 2011

(PhysOrg.com) -- The diamond weevil (Entimus imperialis), also called sometimes as the Australian weevil, is a bug known throughout Australia as a pest, (another close relative resides in South America) as are ...

Recommended for you

Yellowstone's thermal springs—their colors unveiled

Dec 19, 2014

Researchers at Montana State University and Brandenburg University of Applied Sciences in Germany have created a simple mathematical model based on optical measurements that explains the stunning colors of ...

User comments : 15

Adjust slider to filter visible comments by rank

Display comments: newest first

gmfr
5 / 5 (1) Jan 08, 2013
In before "OMG, it's color, not colour!" :)
FainAvis
3 / 5 (4) Jan 08, 2013
gmfr Story is from Western Australia. We spell to English standards, not American. "Colour" is correct.
that_guy
1 / 5 (3) Jan 08, 2013
The depth of these bands can be reduced (the diamond can be 'bleached') under ultraviolet illumination of the diamond and can be restored with longer-wavelength light'.


This is an interesting affect. So, I would imagine that many diamond's colors can be temporarily or semi-permanently altered by a strong light or laser of certain wavelength. (And I imagine that most would return to normal after a period of exposure to ambient light/daylight)

So imagine shining a star shaped UV laser on a pink diamond, and then you get a diamond with a white star in the middle. you could really use this concept for some tremendous effects.

PS. British English spelling is pompous, and there is utterly no reason to add the 'u' in color where no 'u' is needed.
Moebius
2.3 / 5 (3) Jan 08, 2013
Pompous? typical american arrogance, why the world loves us so much. English originated there not here. Americans aren't the gods of the universe though they act like it when visiting other countries. We're so arrogant we change the spelling of countries names to suit ourselves.
rlarg
not rated yet Jan 08, 2013
We are not all that way, this was an interesting and enlightening article sorry for that persons attempt at a comment. I am American to my soul.
jonnyboy
1 / 5 (2) Jan 08, 2013
just say you don't know.....no need to publish it to the whole world,
that_guy
3.7 / 5 (3) Jan 08, 2013
@Moebius and other commonwealth citizens - lighten up. It should be obvious that these comments about "Colour" should be taken lightheartedly, just like I don't get butthurt when you say that it's stupid that we still use miles instead of kilometers in the US. There are many unnecessarily complicated things in all versions of English (And indeed in many aspects of all cultures), and the extra 'u' there just happens to be one small example.

If you don't realize that this banter should not be a big deal, then you need to find yourself a sense of proportion.

http://www.colour...g-battle
finesight
not rated yet Jan 09, 2013
Who would want to bleach out the charm of pink world in a pink diamond? I do not see the point of valuing a gem unles it is for their earth history (and of course durability or beauty). I wonder at such plastic ideas inindustry.
that_guy
not rated yet Jan 09, 2013
@finesight - the purpose to 'bleach' in the article was for scientific/research reasons.

My suggestion was to use it to add patterns and uniqueness to the color and lighting of the stone. And as this is a temporary, plastic, reversible process, you do not have to worry about 'ruining' the stone.

Why not?

Alternately, the opposite process could be used to make some stones more pink and vivid until the sunlight washes it out.
packrat
3 / 5 (2) Jan 12, 2013
That ability could give diamonds a data storage and retrieval capability maybe?
Torbjorn_Larsson_OM
5 / 5 (1) Jan 13, 2013
Well, tickle me diamond pink!
rkolter
not rated yet Jan 15, 2013
A white star in a pink diamond would be pretty interesting. What they didn't say was what the definition of 'bleaching' and 'restoring' were. I did not read it as a physical change in the stone.

I would like to point out that we Americans -should- get butthurt for using miles instead of Kilometers, even if it's by people who can't even spell 'color' correctly. ;)
that_guy
not rated yet Jan 15, 2013
@rkolter.

I think the definition of bleaching and restoring should be clear. Bleaching is the reducing of color, and restoring would do the opposite. Based on the description, it appears to be a photochemical effect that would eventually reach an equilibrium to its 'natural' color again once it had been exposed to full spectrum sunlight for long enough.

I'm sure that a chemistry/atomic physics nut could shed more light than me though.
rkolter
not rated yet Jan 16, 2013
@that_guy -

Let me clarify. It is an old jeweler's trick to use different wavelengths of light to make a diamond appear clearer or enhance a fancy diamond's color. That is why you should only buy diamonds that you view through full spectrum light. IE: never buy diamonds from a store in the mall where there's no window to take the diamond over to.

So - did these scientists identify that ultraviolet light made the diamond appear bleached, and selectively adding longer wavelengths made the diamond's color appear to return? That would be interesting in and of itself.

Or, did they find that ultraviolet light made the diamond less-pink when the ultraviolet light source was removed? That would be interesting too, and lead to the 'white star/pink diamond' suggestion someone else made.
that_guy
not rated yet Jan 16, 2013
@that_guy -

Let me clarify. It is an old jeweler's trick to use different wavelengths of light to make a diamond appear clearer or enhance a fancy diamond's color....
Or, did they find that ultraviolet light made the diamond less-pink when the ultraviolet light source was removed? That would be interesting too, and lead to the 'white star/pink diamond' suggestion someone else made.

From what I read, the way they did it with the pink diamond appeared to be semi-permanent (But reversible). Course, I could be wrong.

I made the white star pink diamond comment :)

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.