Cat''s eye--chrysoberyl?

[glitterata]

Date: 10/19/2009 12:50:24 PM
Author: zeolite
Notice how quickly my eye goes from white to the body color. Notice how your eye has a much wider white transition from the eye to the body color. That is a measure of how tiny or large the inclusions are that make up the the eye. Chrysoberyls have the finest, tiniest inclusions, which give them the sharpest eye. But that is a good indication, not proof. A spot refractive index would instantly separate the two gem species.

But isn''t a lot of that the milk-and-honey effect? In your photo, the light source is directly over the eye. In mine, it''s slightly off-center--see how the sun reflects slightly to the right of the line of the eye?

Where would I find a gemologist who can do a spot refractive index test? What does the test involve? Is it something I can walk into a jewelry store and ask them to do, or do I need to make an appointment with an appraiser?

 

[Richard Sherwood]

A minority of jewelry stores have a gemologist on staff. You could call around.

You might be better served by an appraiser though, especially since you've got that alexandrite possibility going on. That does appear to be a bonafide color change (versus a color shift).

Your new measurements put it in the ~ 1.25 - 1.35 carat neighborhood.

 

[Richard Sherwood]

That''s a nice looking chrysoberyl catseye you''ve got there, Mr. Z.

 

[T L]

Date: 10/19/2009 2:45:28 PM
Author: Richard Sherwood
That''s a nice looking chrysoberyl catseye you''ve got there, Mr. Z.

Yes, ditto on that. I think it was looking back at me!!

 

[glitterata]

I just called David Wolf to try to make an appointment. He was sweet, but he told me that his minimum charge was $150, that small cats eyes weren't worth enough for it to be worth bothering unless they were "gemstones," and that nobody would have set a gemstone in a stick pin like that, even back in the 1890s.

He said "the best way to find out what it's worth is to sell it and see how much you get." Which is not something I'm interested in doing--I don't care so much what it's worth, I care what it IS. (And I plan to keep it!)

I think he thought I was an ignoramus and didn't want me wasting his time.

Can anybody recommend a less important appraiser in NYC who wouldn't find this a waste of time? Preferably one with a lower minimum than $150.

 

[zeolite]

Date: 10/19/2009 1:48:38 PM
Author: glitterata

Date: 10/19/2009 12:50:24 PM
Author: zeolite
Notice how quickly my eye goes from white to the body color. Notice how your eye has a much wider white transition from the eye to the body color. That is a measure of how tiny or large the inclusions are that make up the the eye. Chrysoberyls have the finest, tiniest inclusions, which give them the sharpest eye. But that is a good indication, not proof. A spot refractive index would instantly separate the two gem species.

But isn''t a lot of that the milk-and-honey effect? In your photo, the light source is directly over the eye. In mine, it''s slightly off-center--see how the sun reflects slightly to the right of the line of the eye?

Where would I find a gemologist who can do a spot refractive index test? What does the test involve? Is it something I can walk into a jewelry store and ask them to do, or do I need to make an appointment with an appraiser?

milk and honey effect? No. The milk will be on only the side away from the light, not both sides of the eye. It''s off center. Wouldn''t matter. The milk and honey transition line will always be at 90o to the light source.

In the picture below, I''m showing both in the milk and honey orientation. The strength of the effect is night and day between the two stones. Also notice that I cloned out your thread caught on the prong. I did this to show how effortless it is to manipulate a digital photo.

Thank you Richard. My gem is 1.66 cts. I searched for 20 years, finding low quality at say $300/ct wholesale, fine larger ones at $4,000/ct, and no middle quality. Finally one year a large number of catseyes came onto the market, and there was a huge selection. I finally found one in a middle price range. That dealer had 30 stones to select from, in my size and price range.

 

[glitterata]

Mr. Zeolite, I'm not sure I understand. Are you suggesting that someone manipulated these photographs? I took them myself, and I didn't do any manipulation (besides cropping and rotating).

Your chrysoberyl is obviously a much better stone than my whatever-it-is. Mine has a crooked eye, for example. But the eye looks very thin to me when I look at it in person in bright sunlight, even though I'm not great at taking photographs. (The photos with the broad eye, like the one you show above, were not taken in bright sunlight.) Maybe I should be comparing mine to a similar quality one, not to your gorgeous one. Or doesn't that make a difference?

I just took a the mystery pin to a couple jewelry shops in the neighborhood on my way home from the drugstore.

The first one sells lots of pretty antique jewelry (for too much money).
Me: Do you have a gemologist on staff?
Saleswoman: A what?
Me: Okay, let me ask you a different question. What is this stone?
Saleswoman: That's a cat's eye.
Me: Yes, but what kind of cat's eye?
Saleswoman: What do you mean?
Me: There are different kinds of cat's eyes. Is it a quartz cat's eye? Tourmaline? Alexandrite? Something else?
Saleswoman: Just a minute. [She takes the pin to the back of the shop and comes back in a few seconds.] He says it's a chrysoberyl cat's eye. My girlfriend has one of those--a great big stone. Yours is green. They're usually yellow.

The next shop has a sign in the window saying they do appraisals. They also do very competent repairs (I've used them). Family-owned business, several generations working in the shop. They've had a watch of mine for repair for several weeks, so I stop in to inquire about it. The jeweler apologizes and explains that the watchmaker is off today and he's waiting for some parts.

Me: Can I ask you a question? What is this stone?
Jeweler: That's something called a tiger's eye.
Me: Are you sure? I think it's a chrysoberyl.
Jeweler: Let me see. [He loupes it.] No, this is a green star sapphire. A very nice one.
Me: Do you maybe have a gem tester?
Jeweler: Yes, but it only works for diamonds. I would have to send this to the lab.

I clearly need a gemologist.

 

[LD]

Okey dokey - I have a silly question for Mr Zeolite and Richard if they don''t mind?

Obviously I understand that Alexandrite is the coloour change arm of the Chrysoberyl family etc etc (I''m sure I haven''t used the correct term so please excuse me). However, my understanding is that Chrysoberyl tends to be more yellow and doesn''t change colour. Alexandrite changes colour which is the differentiator. Soooooooooo, are there Chrysoberyl cat''s eyes (i.e. yellow/brown in colour) and then Alexandrite cat''s eyes (green/purple with colour change) .....

OR

Are the two just called Chrysoberyl cat''s eyes irrespective of whether they change colour?

I always thought the two were distinctly different (because of the colour change) but am happy to stand corrected!

 

[Kismet]

This thread made me go take pictures of my chrysoberyl cat''s eye and my alexandrite cat''s eye. It''s funny that the camera picked up a nice sharp eye on the alex on the black background when I wasn''t seeing that at all. I think the camera couldn''t handle the contrast between the light chrysoberyl and the black background.

 

[T L]

There are actually alexandrite cat''s eyes LD. I purchased one many many years ago, and asked an experienced gemologist about it who said they do exist, are rare, but they''re not all super valuable. It depnds on the degree of color change and the sharpness of the eye. However, he told me they do exist. I ended up returning the stone since I wasn''t enamored with it. It''s a double phenomena stone (color change and cat''s eye effect).

 

[Kismet]

On the light background the stones are looking a bit more like what I see in person (although the chrysoberyl eye is nicer in real life.)

 

[LD]

Date: 10/19/2009 5:26:25 PM
Author: tourmaline_lover
There are actually alexandrite cat''s eyes LD. I purchased one many many years ago, and asked an experienced gemologist about it who said they do exist, are rare, but they''re not all super valuable. It depnds on the degree of color change and the sharpness of the eye. However, he told me they do exist. I ended up returning the stone since I wasn''t enamored with it. It''s a double phenomena stone (color change and cat''s eye effect).

Thank you TL but this leads me on a bit more.

So what if they don''t change colour?

You can see from the one I''ve posted that the eye is relatively sharp and there''s a colour change BUT for the life of me, there''s no milk/honey effect.

That''s what made me ask the question ......... I was wondering if you see the milk/honey effect more in the non-colour changers i.e. so what I would deem chrysoberyl cat''s eye?

It would make sense if there were two types because chrysoberyl doesn''t change colour but alex does!

 

[glitterata]

LovingDiamonds, I wonder whether you would see a milk-and-honey effect if you oriented the stone differently.

When the sun is out, hold the stone in sunlight so that the sun is shining on it from the side. You want the sun''s rays to hit the stone perpendicular to the eye. Does that make sense?

If the sun is down, try it with a bright lamp. Make sure the lamp is the only light source in the room.

 

[LD]

Date: 10/19/2009 5:39:18 PM
Author: glitterata
LovingDiamonds, I wonder whether you would see a milk-and-honey effect if you oriented the stone differently.

When the sun is out, hold the stone in sunlight so that the sun is shining on it from the side. You want the sun''s rays to hit the stone perpendicular to the eye. Does that make sense?

If the sun is down, try it with a bright lamp. Make sure the lamp is the only light source in the room.

You do realise I''m in the UK??????

Sun? What''s that then?

 

[glitterata]

My color-changing mystery stone turns out to have the milk-and-honey effect after all--it just needs the right lighting to bring it out.

Here it is with the sun coming from the right-hand side of the picture:

 

[glitterata]

Date: 10/19/2009 5:41:42 PM
Author: LovingDiamonds

Date: 10/19/2009 5:39:18 PM

Author: glitterata

LovingDiamonds, I wonder whether you would see a milk-and-honey effect if you oriented the stone differently.


When the sun is out, hold the stone in sunlight so that the sun is shining on it from the side. You want the sun''s rays to hit the stone perpendicular to the eye. Does that make sense?


If the sun is down, try it with a bright lamp. Make sure the lamp is the only light source in the room.

You do realise I''m in the UK??????

Sun? What''s that then?

Clearly it''s time to take a trip to Spain!

Look at Kismet''s lovely alex. It''s showing milk-and-honey--the side that the light is coming from is darker than the side away from the light.

 

[glitterata]

Kismet, does your alex have zoning? Is that why, aside from the milk-and-honey, one half is bluer than the other half?

 

[Kismet]

Date: 10/19/2009 5:48:05 PM
Author: glitterata
Kismet, does your alex have zoning? Is that why, aside from the milk-and-honey, one half is bluer than the other half?

No I think it''s fairly uniform in color. The lighter bit I think is a reflection of my hand (I was holding a piece of tissue paper in front of the light to filter it a bit.)

 

[zeolite]

Date: 10/19/2009 4:57:10 PM
Author: glitterata
Mr. Zeolite, I'm not sure I understand. Are you suggesting that someone manipulated these photographs? I took them myself, and I didn't do any manipulation (besides cropping and rotating).

Your chrysoberyl is obviously a much better stone than my whatever-it-is. Mine has a crooked eye, for example. But the eye looks very thin to me when I look at it in person in bright sunlight, even though I'm not great at taking photographs. (The photos with the broad eye, like the one you show above, were not taken in bright sunlight.) Maybe I should be comparing mine to a similar quality one, not to your gorgeous one. Or doesn't that make a difference?

I just took a the mystery pin to a couple jewelry shops in the neighborhood on my way home from the drugstore.

The first one sells lots of pretty antique jewelry (for too much money).
Me: Do you have a gemologist on staff?
Saleswoman: A what?
Me: Okay, let me ask you a different question. What is this stone?
Saleswoman: That's a cat's eye.
Me: Yes, but what kind of cat's eye?
Saleswoman: What do you mean?
Me: There are different kinds of cat's eyes. Is it a quartz cat's eye? Tourmaline? Alexandrite? Something else?
Saleswoman: Just a minute. [She takes the pin to the back of the shop and comes back in a few seconds.] He says it's a chrysoberyl cat's eye. My girlfriend has one of those--a great big stone. Yours is green. They're usually yellow.

The next shop has a sign in the window saying they do appraisals. They also do very competent repairs (I've used them). Family-owned business, several generations working in the shop. They've had a watch of mine for repair for several weeks, so I stop in to inquire about it. The jeweler apologizes and explains that the watchmaker is off today and he's waiting for some parts.

Me: Can I ask you a question? What is this stone?
Jeweler: That's something called a tiger's eye.
Me: Are you sure? I think it's a chrysoberyl.
Jeweler: Let me see. [He loupes it.] No, this is a green star sapphire. A very nice one.
Me: Do you maybe have a gem tester?
Jeweler: Yes, but it only works for diamonds. I would have to send this to the lab.

I clearly need a gemologist.

Glitterata,
You are completly misunderstanding me, and so I am at at fault for not making this clear. I am not suggesting that anyone manipulated the photos. I was only using your best milk and honey photo to compare to mine. While doing so, I noticed the thread on your prong. I took the opportunity to clone it out, and while doing so, had a chance to demonstate that the manipulation can't be detected. Removing the prong thread had nothing to do with this subject.

But the eye looks very thin to me when I look at it in person in bright sunlight yes, I said sunlight gives the best eye.

The photos with the broad eye, like the one you show above, were not taken in bright sunlight. Yes, but these were the only pictures where you showed your milk and honey effect.

Maybe I should be comparing mine to a similar quality one, not to your gorgeous one. Or doesn't that make a difference? Yes, it does make a difference. But I was trying to show that even a low quality chrysoberyl cats eye has a sharper eye that other catseye gems.

Yours is green. They're usually yellow. Chysoberyl cateyes can be brown, pastel yellow or pastel apple green. I don't thnk they can be dark green.

That's something called a tiger's eye. Tiger's eye is a banded cryptocrystalline quartz. The eye is fixed and does not roll across the dome like any catseye gem.

this is a green star sapphire Rolls his eyes. Star sapphire has 6 rays, not one band.

I clearly need a gemologist Yessss!!! Let me make one distinction which Richard can help me with. A gemologist can scientifically identify gemstones. Appraisers can assign a dollar value to the gem. They are not the same. Richard has been too polite to suggest that you submit it to him. Since he is a GG, he can identify it, but as an appraiser, can assign value, especially for a rare gem such as a gem that is both catseye AND Alexandrite.

 

[zeolite]

You people are asking questions faster than I can type.

What does the test involve? Is it something I can walk into a jewelry store and ask them to do, or do I need to make an appointment with an appraiser?

They place the refractometer on a table, point a light source behind it, place a drop of RI fluid on the refractometer, remove the front lens of the refractomer, place the dome of the gem on the fluid drop, and read the refractive index. Takes one minute. Jewelers with gemologists need to make a profit, but $150 minimum is ridiculous.

Another point: it may take, say 6 or 7 measurements to prove it is a specific gem, but it only takes one test to prove what it isn’t. If it reads R.I. =1.65 (cats eye enstatite) it is not a chrysoberyl.

 

[glitterata]

Ahhhh, I understand about the photo manipulation now. Sorry I was so dense, and thank you for giving my pin a haircut.

If Richard weren''t a thousand miles away in Florida, I would send my pin to him in a New York minute! If I don''t find someone soon who can give me a more scientific answer than "tiger''s eye" and "star sapphire," I may just do it anyway.

Meanwhile, a friend with some expertise and equipment has offered to help ID the stone. (She can''t give me a value, but I already know the value: $11, plus shipping, minus three other stickpins. After all, I won it in a fair auction, so it''s worth what I paid for it.)

 

[zeolite]

LD: I understand that Alexandrite is the colour change arm of the Chrysoberyl family …Chrysoberyl tends to be more yellow and doesn''t change colour ...Alexandrite changes colour which is the differentiator. OR Are the two just called Chrysoberyl cat''s eyes irrespective of whether they change colour?

The chemical formula for chrysoberyl is BeAl2O4. That is, it is composed of beryllium, aluminum and oxygen. Most chrysoberyl is brown, yellow, greenish-yellow or green, and doesn’t change color under different light sources. However, if it contains trace amounts of chromium or vanadium, it can be a more intense green or blue-green in daylight and purple to purplish-red to red under incandescent light. This color change version is called alexandrite. But it is still just chrysoberyl. The vanadium or chromium creates an absorption band in the yellow region, which is the cause of the color change.

Chrysoberyl can have many tiny inclusions, which line up with the crystal structure. These included forms of chrysoberyl are called cats eyes, but they are still just chrysoberyl.

Extremely rare chrysoberyls can contain both trace amounts of chromium or vanadium, AND visible inclusions. These are properly called cats eye alexandrites. But they are still just chrysoberyl.

 

[Richard Sherwood]

Date: 10/19/2009 5:20:56 PM
Author: LovingDiamonds
Okey dokey - I have a silly question for Mr Zeolite and Richard if they don''t mind?

Obviously I understand that Alexandrite is the coloour change arm of the Chrysoberyl family etc etc (I''m sure I haven''t used the correct term so please excuse me). However, my understanding is that Chrysoberyl tends to be more yellow and doesn''t change colour. Alexandrite changes colour which is the differentiator. Soooooooooo, are there Chrysoberyl cat''s eyes (i.e. yellow/brown in colour) and then Alexandrite cat''s eyes (green/purple with colour change) .....

OR

Are the two just called Chrysoberyl cat''s eyes irrespective of whether they change colour?

I always thought the two were distinctly different (because of the colour change) but am happy to stand corrected!

You are correct. Both are the mineral chrysoberyl, with the color change differentiating the alexandrite from the non-color change chrysoberyl.

Hence you have chrysoberyl catseye and alexandrite catseye. An alexandrite will always be a chrysoberyl, but a chrysoberyl is only an alexandrite when it has the color change.

 

[Richard Sherwood]

Hey Glitterata, you can send me that mystery stone if you like. I''ll do the identification at no charge just out of curiousity. I only use Fedex for return delivery though, which would cost you about $40 for return shipping and insurance (using 2nd day Air).

 

[zeolite]

Date: 10/19/2009 5:26:25 PM
Author: tourmaline_lover
There are actually alexandrite cat''s eyes LD. I purchased one many many years ago, and asked an experienced gemologist about it who said they do exist, are rare, but they''re not all super valuable. It depnds on the degree of color change and the sharpness of the eye. However, he told me they do exist. I ended up returning the stone since I wasn''t enamored with it. It''s a double phenomena stone (color change and cat''s eye effect).

The principal difference here is that the properties that make a good catseye are somewhat contradictory to what makes a good color change stone. Trying to get both properties at once is mutually exclusive.

A fine cats eye has the eye centered in the stone, and there is only one orientation that does that, with the base parallel to the row of inclusions. A good catseye can''t be too included or it has no translucency. It can''t be too clean, since it will have no inclusions and no eye. Also a catseye needs the bundle of inclusions to show the milk and honey effect.

Consider a fine color change stone: It should have no inclusions at all, since that hurts the brilliance. It is a tri-chroic stone, showing three different colors when viewed in 3 different directions. Yet it should be oriented only in one direction(I think green, not sure). This orientation probably will not be in the correct direction (with the inclusions parallel to the base).

So the rare (but typical) cats eye alexandrite shows both weak color change, a weak eye, and perhaps no milk and honey. It is too much of a compromise and doesn''t do any of the three effects well.

 

[glitterata]

Date: 10/19/2009 7:07:55 PM
Author: Richard Sherwood
Hey Glitterata, you can send me that mystery stone if you like. I''ll do the identification at no charge just out of curiousity. I only use Fedex for return delivery though, which would cost you about $40 for return shipping and insurance (using 2nd day Air).

Rich, thank you for that incredibly generous offer! If I do send it to you, I would like to pay you for your time--this is what you do for a living, and I already feel like I mooch off your expertise enough! I''m going to see my friend with the refractometer tomorrow, I hope, so maybe I won''t need to send it all the way to Florida. Presumably she will be able to rule entstatite in or out.

If it does turn out to be chrysoberyl, will that automatically mean it''s alexandrite, or does the degree of color change need to be assessed subjectively by someone experienced with making that kind of judgment call? If so, my mystery stone may soon be winging its way to you.

Mr. Zeolite, I''m sure I''m speaking for lots of us when I say THANK YOU for all your fascinating and informative posts on this topic. It''s been really fun and educational.

 

[Richard Sherwood]

Yeah, I enjoy your posts too, Mr Z.

Glitterata, if the stone is chrysoberyl I''d have to see it before identifying it as alexandrite or not. The ID would include a spectrophotometer analysis to determine the trace elements of the stone (chromium in particular), and then a visual assessment of whether the color change is significant enough to classify it as alexandrite.

There are chrysoberyls (which are not alexandrites) that have different perceived appearances under fluorescent and incandescent lighting. This is a color "shift" due to the lighting rather than a true color change.

 

[chrono]

LD,
I’m not expert but my understanding is that there are colour shift chrysoberyl that shift from yellow to green. I have also seen chrysoberyl cat’s eyes so it is possible that they also colour shift. I purchased an Alexandrite cat’s eye not too long ago. They do exist, are rare but for some unknown reason, not terribly expensive. The colour change on mine was very good, the cabochon quite translucent and the eye sharp. It also has a decent bluish green colour that changed to a very rich reddish purple. It came complete with the milk & honey effect as well. Sadly, I returned the cat’s eye alexandrite because I was concerned about CS shrinkage syndrome.

 

[chrono]

Glitterata,
I’m sorry I had a chuckle at your expense. I really doubt your stone is a tiger’s eye or green star sapphire. It doesn’t have the characteristics that mark it as such.

 

[LD]

Mr Z and Rich - very very very many thanks for confirming that I''m not going potty!!! I really was getting utterly confused by the posts and thought that everything I had learned to date about Alex needed to be thrown out of the window and started again! Thankfully you''ve confirmed that''s not the case!

Glitterata - I''m really intrigued by your mystery stone. I''d put good money on it being an Alex with a weak colour change! Please keep us updated won''t you? I think Rich''s offer is incredibly kind and just goes to show what a great community PS is.