My new blue sapphire changes color with orientation - need input please

[CaseyLouLou]

Hi All,

I received a new, velvet blue sapphire today. It is a 1.1ct cushion with a velvet blue color. Upside down it has some significant zoning but from above it is not noticeable.

The sun isn’t out today which is unfortunate but I took some photos near a window. I noticed the strangest thing…when I hold it horizontally it glows a pretty velvet blue color but when I turn it vertical it goes dark. It’s not half and half either. It’s the whole thing that changes. It becomes less glowy.

I tried to capture it in photos and I think you can see what I mean but the darker one looks worse in real life. The glowy one is true to the color I see.

Is this common in sapphires? I have heard they need to be cut a certain way because of orientation of the crystal so did something go wrong with this one or is this just how it goes? I think it would need to be mounted horizontally to be worth setting.

 

[CaseyLouLou]

More photos.

 

[Rfisher]

I do think that looks like extinction. (Just not half/half extinction)
from what I see in your photos.

 

[demantoidz]

If you turn it upside down, is the color difference when viewed horizontally vs vertically still there? If yes, it might be pleochroism, otherwise I would guess its a cutting thing.
I have a stone whose color looks the same face up but pleochroism is obvious when placed upside down and looked at from different angles.
I don't know much about pleochroism in corundum so I should read up about it.

 

[CaseyLouLou]

If you turn it upside down, is the color difference when viewed horizontally vs vertically still there? If yes, it might be pleochroism, otherwise I would guess its a cutting thing.
I have a stone whose color looks the same face up but pleochroism is obvious when placed upside down and looked at from different angles.
I don't know much about pleochroism in corundum so I should read up about it.

It looks very different upside down because of the zoning. One end has very little color. It’s super gloomy out today so I will have to wait for tomorrow to see it’s true potential. If in bright light it looks fine vertical then maybe it will be fine. I’m not sure I want to set it horizontally.

I have been reading about pleochroism and extinction and it’s not helping yet but the 90 degree change is fairly dramatic so I’m guessing it has something to do with it. Or extinction angles or something.

 

[Autumn in New England]

First of all, that stone appears to have great color to these eyeballs! I am in agreement that what we're likely seeing is extinction, and that is attributable to the cutting technique. It's almost impossible to have a well-saturated blue sapphire with zero extinction. And most of them are native cut. No stone looks its absolute best from every angle. That being said, if this issue continues to bug you, you might consider returning the stone. Whenever I've been stuck on even an infinitesimal issue from the start, it's never resolved itself, and the stone inevitably ends up in my "for sale" pile. Good luck!

P.S. I feel I should also add a disclaimer that the color zoning could be the cause, since you said it's rather dramatic. And maybe that is giving the illusion of dichroism. But a "color change" sapphire would have more to do with a hue change under different lighting temps.

 

[LilAlex]

Depending on the angle of the incident light (meaning I can not tell what the environment looks like), it could be that it is dichroic.

Sapphire can have "different" colors in different orientations.

Here is a nice explanation from Lotus:

Pleochroism in Faceted Gems • An Introduction • Lotus Gemology

Colored gem testing, including origin and treatment identification for ruby, sapphire, spinel, emerald and jade from Lotus Gemology

www.lotusgemology.com

The "best" sapphires are cut so that the face-up view is not impacted by dichroism (the so-called c-axis runs vertically through the table and culet, IIRC) -- although they may look different from the sides. But since the often-barrel-shaped corundum crystal is faceted however best preserves weight and capitalizes on the bluest material in the crystal, it is not hard to envision a configuration that lets dichroism influence the face-up color.

 

[Ionysis]

Very common to have this in sapphires. Sometimes the cut which “optimises” the colour in certain conditions also has its opposing effect in different lighting or angles.

It can be possible for cutter to get a more uniform performance - but that then becomes a stone which is middling across the board rather than super glowy in some lights and dark in others. I’ve seen people have native cut sapphires recut into a more symmetrical / precision style which has had the effect of taking all the personality out of the stone - even changing the hue and tone for the worse. Often these native cutters have decades of experience. The stone may not look symmetrical but boy do they know how to get colour out of it.

Personally I’d rather have the changeable stone which stuns in some lights / conditions than the one which is uniformly “OK”. This is one of the reasons I love sapphires - each has its own personality and idiosyncrasies.

I think you have a beautiful stone there. And east west is my favourite setting too!

 

[CaseyLouLou]

Very common to have this in sapphires. Sometimes the cut which “optimises” the colour in certain conditions also has its opposing effect in different lighting or angles.

It can be possible for cutter to get a more uniform performance - but that then becomes a stone which is middling across the board rather than super glowy in some lights and dark in others. I’ve seen people have native cut sapphires recut into a more symmetrical / precision style which has had the effect of taking all the personality out of the stone - even changing the hue and tone for the worse. Often these native cutters have decades of experience. The stone may not look symmetrical but boy do they know how to get colour out of it.

Personally I’d rather have the changeable stone which stuns in some lights / conditions than the one which is uniformly “OK”. This is one of the reasons I love sapphires - each has its own personality and idiosyncrasies.

I think you have a beautiful stone there. And east west is my favourite setting too!

I really appreciate all of the advice and info from everyone.

I was able to view this sapphire in better lighting and it doesn’t seem to have that issue as dramatically. It seems that whenever I get a new stone I tend to look for every flaw and it didn’t help that it was a rainy, gloomy day.

I took a couple of new photos but need to get some better ones. I think this one is a keeper though.

 

[Autumn in New England]

I really appreciate all of the advice and info from everyone.

I was able to view this sapphire in better lighting and it doesn’t seem to have that issue as dramatically. It seems that whenever I get a new stone I tend to look for every flaw and it didn’t help that it was a rainy, gloomy day.

I took a couple of new photos but need to get some better ones. I think this one is a keeper though.

I do the same thing... it's important to be thorough in your initial examination of a new stone. But it's also easy to become overcritical. I think it looks beautiful!!

 

[Frost]

What you're looking at is light return, and that's expected behavior for any blue rectangular cushion with a medium or darker tone - it's just how they return light in that cut when those two orientations are compared. This change is entirely a function of cut design.

Sapphires (and spinels, garnets, etc. etc.) don't light up the same in every orientation, most cut designs simply aren't meant for it. The closest you can come to a uniform overall light return is in rounds or squares, but practically any other cut will have differences in how light is returned based on how you rotate it.

It's almost always a case of either-or: barring rounds, squares, trillions and very rounded ovals, any other cut will tend to light up entirely in the orientation it's designed to be viewed in and light up much less in the opposite one.

As an example, a well cut rectangular cushion or oval of a medium to medium dark tone will light up well East-West while not looking too great North-South. A similar supernova oval might light up beautifully North-South, but have patches of dark extinction East-West. And so on.

Also, a darker tone/more saturated hue may impact how easily visible it is and cut quality may impact light return in the "intended" orientation (but will not prevent the change itself from occurring or exacerbate it in the other one). The one exception to this would be that ironically, really badly cut stones with windows sometimes actually look less extinct since light passes right through them so they have no place to show extinction (but also nowhere to show the missing color).

 

[Ionysis]

Did you decide to keep it?

 

[CaseyLouLou]

Did you decide to keep it?

I did keep it. I decided it was a pretty color I have learned that darker sapphires tend to look best in bright light. On day 1 it was rainy and I also wasn’t expecting the orientation phenomenon but when I played with it it better lighting it’s a very bright, velvety blue. It does have a bit of a bow tie but that also disappears in the right light. Hopefully someday I can figure out a setting that will show off the color the best way possible.