GemologyOnline.com
https://www.gemologyonline.com/Forum/phpBB2/

Blue colour change garnets
https://www.gemologyonline.com/Forum/phpBB2/viewtopic.php?f=20&t=24328
Page 1 of 2

Author:  Raj_uk [ Thu Mar 15, 2018 10:58 am ]
Post subject:  Blue colour change garnets

Just wanted to share, Im a big fan of garnets so I was pretty happy to get a small parcel of these recently.

Not very big, just over 1ct each.

Image

Image

in daylight, white led light, and incandescent

Author:  dchallener [ Thu Mar 15, 2018 5:09 pm ]
Post subject:  Re: Blue colour change garnets

Those are TRULY nice - and a carat size is quite large for a blue garnet!

Author:  Barbra Voltaire, FGG [ Thu Mar 15, 2018 10:30 pm ]
Post subject:  Re: Blue colour change garnets

Impressive.
What light sources are you using?

Author:  Raj_uk [ Fri Mar 16, 2018 12:09 pm ]
Post subject:  Re: Blue colour change garnets

thanks!

I have more but they are slightly greener.

Light sources were - daylight, white led light / fluorescent, and incandescent

Author:  Barbra Voltaire, FGG [ Fri Mar 16, 2018 8:30 pm ]
Post subject:  Re: Blue colour change garnets

Were you able to get the specs on the stones?
Refractive Index?
Inclusion scene?

Author:  dchallener [ Fri Mar 16, 2018 8:44 pm ]
Post subject:  Re: Blue colour change garnets

Can you give us the dimensions?

Author:  Stephen Challener [ Fri Mar 16, 2018 9:26 pm ]
Post subject:  Re: Blue colour change garnets

The needle inclusions on the first stone are very diagnostic for garnet I think. I have a similar (though much more included) example.

Author:  Raj_uk [ Sat Mar 17, 2018 1:19 pm ]
Post subject:  Re: Blue colour change garnets

Agree, the needle inclusions are pretty common in garnet. Coincidentally that one sold pretty quick.
Unfortunately no RI or Lab tests, brought from my source in Asia on my travels just last week. African origin, most likely Madagascar?

Ive managed to take pictures of the rest of the parcel now so Ill give dimensions also -

Image

1.28ct (from initial post)
6mm / 5mm / 5mm

Image

1.2ct
6.5mm / 5mm / 4mm

Image

1.08ct
6.5mm / 5mm / 3mm

Now the greener ones. Ive seen internet vendors advertise these as blue garnet, but to me if its not a proper blue its not blue. Am I right in my assumptions ? Im unsure why many dealers are selling this as blue.


This one is on the "bluer" side

Image

1.06ct
7mm / 5mm / 3mm

Image

1.15ct
6mm / 5mm / 4mm

Image

1.34ct
6mm / 5mm / 5mm


Now for some terrible photos of inclusions, I need a better macro lens. Or just A macro lens would do.

from the 1.28ct -
Image


1.2ct
Image

The Heart
Image

thanks for looking

Author:  75TURBO [ Mon Apr 02, 2018 11:36 am ]
Post subject:  Re: Blue colour change garnets

You have a background color change also!

Author:  Raj_uk [ Tue Apr 03, 2018 12:43 pm ]
Post subject:  Re: Blue colour change garnets

75TURBO wrote:
You have a background color change also!


that's different lighting mate :roll:

Author:  Isi [ Wed Apr 04, 2018 6:03 am ]
Post subject:  Re: Blue colour change garnets

I understand 75Turbo's feeling. Under completely different lightings, everything is more or less color change, and then you come to question the reality of the color change character in a stone.
It would be interesting to get a picture of another stone, same basic color but NOT color change, close to one of these garnets, under these 3 lightings, so that we could appreciate how one of of the stones changes color and the other does not, even if the background changes too.

Author:  Stephen Challener [ Wed Apr 04, 2018 9:39 am ]
Post subject:  Re: Blue colour change garnets

This is a 100% blog standard issue with photographing cc stones. It really isn't suspicious or unusual. Messing around with the white balance to get the background color consistent isn't necessaroly going to reflect reality any better. There is a reason a lot of sellers just use photoshop to simulate the change.

Author:  Raj_uk [ Wed Apr 04, 2018 6:30 pm ]
Post subject:  Re: Blue colour change garnets

Stephen Challener wrote:
This is a 100% bog standard issue with photographing cc stones. It really isn't suspicious or unusual. Messing around with the white balance to get the background color consistent isn't necessaroly going to reflect reality any better. There is a reason a lot of sellers just use photoshop to simulate the change.


Thank you Stephen, you've pretty much hit the nail on the head. Having taken tens of thousands of pictures of gems in my lifetime, adjusting white balance on the camera never changes the colour of the gem. As you correctly point out only the background gets lighter or darker.

Just for the record these pics were merely cropped and pasted in good old Microsoft Paint : )

Isi, understand what youre saying, Ill try and get some pics up tomorrow ;)

Author:  MADADIDIERITE [ Thu Apr 05, 2018 6:03 am ]
Post subject:  Re: Blue colour change garnets

2 pieces of garnet from BEKILY, MADAGASCAR

Attachments:
bekily02.jpg
bekily02.jpg [ 31.14 KiB | Viewed 3088 times ]
bekily01.jpg
bekily01.jpg [ 40.77 KiB | Viewed 3088 times ]

Author:  Raj_uk [ Thu Apr 05, 2018 7:15 am ]
Post subject:  Re: Blue colour change garnets

Isi wrote:
I understand 75Turbo's feeling. Under completely different lightings, everything is more or less color change, and then you come to question the reality of the color change character in a stone.
It would be interesting to get a picture of another stone, same basic color but NOT color change, close to one of these garnets, under these 3 lightings, so that we could appreciate how one of of the stones changes color and the other does not, even if the background changes too.


Stephen Challener wrote:
This is a 100% bog standard issue with photographing cc stones. It really isn't suspicious or unusual. Messing around with the white balance to get the background color consistent isn't necessaroly going to reflect reality any better. There is a reason a lot of sellers just use photoshop to simulate the change.


As promised.

Initially I tried a purple garnet next to the blue, wrong choice obviously due to garnets tendency to "colour shift".

But you can see the difference between a supposed colour shift, and a real colour change with the blue garnet.

With the purple garnet there is no real visible colour shift to the eye, so that would rightly be questionable.


Image

Next I tried it with an orange zircon, which I know is inert colour wise -

Results as expected, very obvious colour change with the garnet, and the zircon stayed orange.

Image

Overall a worthwhile test :)

Page 1 of 2 All times are UTC - 4 hours
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/