Answers on "Andesine-Labradorite" color source!

[allen]

That's pretty much what I said, though I don't think it is ever used just by itself.
I can't remember if it acts as a flux or a refractory? Any potters lurking about out there?

(I realize this is all pretty silly, but hey, it's dialog)

[colorshapetexture]

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MAKING ARTIFICIAL GEMS; Methods Used by Chemists in Making Diamonds, Rubies, and Other Gems from Their Constituents. TRANSMUTATION IN MINERALS. Prof. Amos P. Brown Tells of the Interesting Experiments Which Have Changed Minerals Under Influence of Fusion

Maybe not so far fetched .... Jim

[Doos]

Here's some new research just in:

http://www.yourgemologist.com/ISGForums ... php?t=3424

Hi Yvonne,

Thanks for sharing and although I was advised not to read the tabloids anymore, I did.
There is a serious problem with the "research" presented.

1. The author posts a spectrograph of "deep red plagioclase" and assumes it is a graph for both red and green labradorite. The images presented clearly show that the graph is derived from red stones, not green ones. The page does not say that the graph is applicable to green as well (although under the red and green header).
2. The author posted the image as proof to make a point without reading the article itself.

Selective reading is one of the traps when looking for evidence.

[stonecrazy]

The author of the new research also stated that it is very complicated to run an immersion test and that the members of this forum are not advanced enough to know the techniques.
All this time I thought all you had to do was get a small Dixie Cup and cut it down to about half an inch tall. Pour in the baby oil. Drop in the gem. Turn on the overhead light on my gem microscope. Run at 30 power. Set the cup under the microscope. Adjust so I can see.
Could somebody please write a detailed proceedure on the Dixie Cup Immersion Test. I have to be doing something wrong as my samples did not look like the ones the Major Research Lab has so elequently documented..

[Doos]

Hi,

Just take a glass cup (preferably strainless) and place it above the transmitted light source of the microscope. You may want the "complicated" diffused light, so place a sheet of toilet paper underneath the glass beaker/cell .. anything. Then look down the oculars and observe the wonders of nature. Cup filled with liquid and gemstone of course.

It is indeed very complicated and you will indeed need about 5 minutes to master this master-level technique. Not for the faint hearted.

From the images in the past newsletter and presented by gemjunkie, they used the same technique.

p.s.: as a warning: make sure the toilet paper will not to get too hot asto set your microscope on fire.

[Barbra Voltaire, FGG]

The author of the new research also stated that it is very complicated to run an immersion test and that the members of this forum are not advanced enough to know the techniques

I personally own 3 German immersion microscopes and was taught to identify gems using horizontal immersion scopes at the DGemG. I've never tried a "Dixie" cup, but in all the andesine/labradorite I have viewed with immersion, I have never seen concentrations of color on the back facets.

I have certainly not seen the broadest cross sampling, perhaps only 50 specimens.
Therefore, is it possible that some show these concentrations?
Obviously, at least one.

All that aside, I have no desire to fuel a rivalry.
That seems like a waste of time for me, as it just diverts our attention away from the task at hand.

I think there is usually room for more than one opinion.
We should be able to critique issues without resorting to low blows.

After all, none of us are runing for president.

[dragonstek]

Hi

i was just checking out info on the website for the International Gem Society " IGS" and they have Andesine RI 1.54- 1.55 bire .008 B+/- AGG ,
with its SG being 2.65-2.69( my scale batteries are dead and i cant check mine) Barbra you still have some pieces ,could you weight them

so if you go back to the 1st report he states the JTV stone RI was biaxial - and the RI 1.52-1.56 might his refractometer be off

and it also states to have some weak pleochroism :
the red orange - orange / light reddish purple
the bluegreen- red-violet/reddish orange/bluish green

UV long n short wave - enert to weak patchy white

im still new at this so i thought maybe someone who had more experience who had a piece could test it

[Barbra Voltaire, FGG]

We started a discussion on this material back in 2005.
Lots of SGs posted there

I breezed though some of these posts and it appears as though most everyone, at that point, accepted these gems on face value.

[Precision Gem]

Isn't measuring the SG with a ct. scale and a beaker of water kind of silly?

If you have a scale that is accurate to 0.01 ct. and measured a stone in air at 1.25 ct., then in water at 1 ct.

the SG would be = 1.00/(1.25-1.00) = 4

But if you apply the accuracty of the scale you could have a solution as high as 4.39 and as low a 3.67

example:

SG = 1.01/(1.24-1.01) = 4.39

or

SG = 0.99/(1.26-0.99) = 3.67

Figure in some frictional losses in your apparatus and the accuracy is even worse.

So unless your scale is much more accurate than this, you solution in not very usefull. That is if we wanted to take a scientific approach.

[Barbra Voltaire, FGG]

Could be a little primitive, Precision Gem, you are correct.

I use my Mettler that is calibrated annually to a percision of .001 for use in the trade, so I have found hydrostatic weighing a pretty useful tool, but I must admit, I take 5-10 submerged readings every time to try to be as accurate as possible.

It is certainly useful in seperating diamond substitutes which have RIs over the limits, but in other cases, simply another possible clue.

[Precision Gem]

The larger the stone, the better. Or better yet a small parcel.

[Barbra Voltaire, FGG]

Absolutely correct! Not surprising, with your background in engineering that you are spot on with your comments.

Small stones can indeed be problematic.

One is handicapped by the sophistication (or lack therof) of the equipment they own, and I guess, by the "girth" of their gems.

[GEMFRANCE]

Hello everybody,

Just coming back after a trip in South Africa, I read all these posts. So one more time I come back to you to give my information as known as the source of “Congo Andesine”.

- All my stones sent to the laboratories were coming back with "Andesine"; never Labradorite or "Andesine-Labradorite"
- All the stone that we have recut shown exactly the same color after recut.
- All the stones that we have are selected as "only the finest". So I can only talk about the top red and red orange. I cannot talk about the stones that I have not selected or tested.
- My stones were confirmed to come from Democratic Republic of Congo, in an area at the south east of Goma. This was also confirmed by an independent geologist.
- Even if I go to Congo, even if I go to the exact area (in the rain forest?) I cannot be sure to have the opportunity to find from where there was coming 5 years after.
- Regarding the quantities that I have seen and bought from my suppliers in this quality, it was coming from only few kilos of rough. So it is almost nothing regarding the feldspar coming from Oregon or the stones said coming from Tibet, Mongolia… China.
- even if I go to this area in Congo and find the rough there, I know that the controversy will be going on because even if I am a geologist, even if I was a professor in University, I am now in the gem trade and I am not from an independent laboratory. And many people will say that I want to save my business... It will not enough to say trust on me, I was there, I have seen and collect samples.
- I have now only a few rough stones. But I have not had these ones by myself on the ground. It was from my suppliers. So I can also trust on my suppliers.
I have given several samples of rough to people and also to Oregon dealers. After months or years I am still waiting for the result of the analysis. Too good to be published? I don't know.
- I think that the information that Labradorite (yellow from Mexico?) could have been heated with cupper in tumblers to obtain red feldspars could be true. But that does not mean that all the red andesine coming from any point in the world, except from Oregon, is not 100% natural…
- regarding The Oregon sunstone, if a treatment exists to obtain red feldspar, why not with Oregon sunstone? Are 100% of the people from Oregon honest and the other people not?
- So:
1/ there is a high probability that the rumour about heat treatment with cupper to obtain “red Labradorite- Andesine” is the truth.
2/ I trust on my suppliers and on the scientist information received about the locality of the source of my andesine: Democratic Republic of Congo.
3/ I think that this source have supplied stones only during 2 years. Why? No more stones, or an area not enough safe regarding the conflicts; I don’t know.
4/ I trust on the laboratories who have checked now about 200 of my biggest andesines and confirmed that they are Andesine and not Labradorite.
5/ My red and red-orange andesine have usually not brownish tone and less platters than the “Chinese” andesine.
6/ Actually nobody can say that 100% of the “Oregon sunstone “or “Congo Andesine” are without any treatment, as nobody can say that 100% of the “Chinese or Tibet or Mongolian sunstone” are treated.
7/ testing feldspar with a refractomer is not enough to say if it is a Labradorite or an andesine. You need chemistry analysis;

I confirm that I have not seen more good quality in Andesine since long time, only a few pieces in small size.

I still have about 1000 pieces less than 1ct, 900 pieces between 1 to3ct, 160 between 3 to 5ct, 130 between 5 to 10ct, and 14 from 10 to 33.42ct. So, you see it is really a rare stone.

I hope that all that will help.
Take care with the rumours!

[Jim]

Gemfrance, it's great to see your back from your trip. I know you will be glad when Dr. Rossman's report comes out in a week. Hopefully it will validate your gemstones.

I'm just a plain spoken person so please do not take this the wrong way. When comparing the oregon sunstone and andesine labradorite I think these are totally different specimens. You can actually go to several sunstone mines and see the rough being pulled from the earth. You can see it as the earth produces it and before human hands have touched it. It is definately made by mother nature. With andesine labradorite who knows? Can you go to the mine location and pull this from the earth in colors of red and green? Now this is just from what I have seen on the web. The one mine that was found on the China/Mongolia border showed rough that was yellow before being heated to produce red color. In their own words, this is the way it comes from the earth as yellow andesine. I have see nothing from the other mine locations on andesine labradorite.

One is produced from nature in red and green and one is produced from nature with a little help from heat treatment. That's the difference I see at this time. Mind you this is only from this one location in China. It is ashamed that the Congo area is ridden with conflict because I would like to see the mine that your gemstones come from. This would stop alot of the speculation on this subject. As I own several of these gemstones, I would like nothing better than to know that these beautiful gemstones from the Congo are the real thing. We will know in about a week. Good luck to everyone involved.

Jim

[GEMFRANCE]

Thanks Jim,

Regarding the Dr. Rossman's report, I don’t know if he will inform about Congo Andesine. If Yes, I don’t remember that he bought stones from my company.

Of course, I trust on Oregon miners. But what I wanted to say if a treatment exists to give a better red color on feldspar, why not for Oregon sunstone. The fact that we can see the stones coming out the mines is not enough. Of course, we can follow the stones step by step.
As I said on a previous post about the Paraiba tourmalines, I know where some rough emeralds from the Muzo mine in Colombia are treated with Opticon. And this rough returns inside at the mine where it is sold as just coming from the ground.