Supposedly alexandrite ring strange case.

[Procer]

Dear Pricescope users.

I have a fun case I would like to share. I have a stone that looks and react likes an alexandrite, color changing in different lights with the right bluish green and peach red.
My results so far are:

Under the chelsea filter it is orange in incandescent light and bluish green in the middle and orange along the girdle in normal light under the same filter.
Under Long wave UV-light red and orange
Under Short wave UV-light it is bluish green.
The RI is= 1.77-176-176.5 and it has an oval shadow while looking through the looking glass.

My conclusion is that this is not a natural alexandrite but a synthetic variant of corundum, but the odd thing I find is that synthetic corundum under short wave UV light normally shows a reddish tone. Has I mis-concluded or is their some corundum variant that shows milky greenish under short wave?

 

[chrono]

Am I reading correctly that under the Chelsea filter, it is bluish green in the middle but shows some orange along the girdle? Do you suspect a doublet stone?

Whatever it may be, the RI and reaction to UV rules out natural alexandrite. It also rules out flux grown alexandrite since that should be the same as a natural alex. The RI falls in line with vanadium laced corundum, however, this type of stimulant usually never shows any green.

 

[Procer]

Yes that was that I meant, I am sorry if I was a bit unclear.

And no never thought of at doublet stone, but I should have, it actually seems rather obvious. Maybe the doublet would also explain why a vanadium laced corundum shows green? If one part of it is something that exhibits color changing properties and another much larger part doesn't?

Update: I made a critical mistake. The stone is green under LED light. purple(amethyst like) under incandescent light and mauve under sun/natural light.

 

[chrono]

Yikes! I meant simulate stone, not a stimulant. Dang my spellchecker.

 

[LD]

Ok - first up, your title suggests that the stone is already in a ring? Is that correct? If so, then I wouldn't base anything on the RI as you really need to unmount the stone to get a clear RI reading.

Under a chelsea filter, an alex will show red because of the chromium content - so I'm confused as to why it would show orange or even green. That to me suggests that this isn't an alex BUT a chelsea filter reaction is really only one clue!

The RI would fit with synthetic corundum - do you see any gas bubbles? They are pretty common with this material (but again not definitive).

You've described the daylight colour as blue/green. With this material it's very rare you see the green associated with a natural alex. It does tend to be more on the blue side so again, it's fitting more with synthetic corundum.

Unfortunately there are many types of simulants/synthetics that resemble Alex and it's incredibly difficult to correctly identify without a host of gemological tests as these now can mimic natural alex in more ways than one.

From what you've said, I would be inclined to agree that it doesn't sound natural but that's just a gut instinct from what you've written and may well be off the mark.

 

[LD]

Oooops it took me a while to type a response and I can see that Chrono has answered all your questions anyway! Sorry for the repetition.

 

[chrono]

LD,
You should never apologize for posting even if you think it sounds repetitive. It’s always good to read varying responses, ideas and hypothesis. Not only that, you know so much more about alexandrites than I could ever dream of knowing.

 

[Procer]

Not a problem I really like the detail in you answer, and I agree with crono

I just have to updated you on the stone, because I made the discovery that the alex shows green under LED-light, purple(almost amethyst like) under incadescent light and mauve under sun/natural light. So it is actually tricolored.

 

[LD]

Thank you Chrono and Procer for your kind words.

Procer - unfortunately one thing about Alex is that the way they react to LED/natural light isn't definitive about anything at all because the synthetics and simulants can react in exactly the same way. With most stones, how they react to light or whether they have fluorescence etc., gives an indication one way or another - with alex it doesn't. It's a heck of a stone to identify correctly without gemological testing.

The only thing you can definitely say about lighting and how that affects alex is that if it isn't green in daylight and purple/red in incandescent then it's not an alex! Some simulants actually show the reverse effect and so you can rule them out. Now the one thing that you've said that makes this categorically NOT an alex is that in sunlight (and it doesn't matter how strong) it would always show green and never purple. So the fact that yours shows mauve in sunlight means it isn't a natural alex.

Irrespective of what it is/isn't, it sounds very pretty so I would keep hold of it just because it sounds, and presumably looks, lovely

 

[Procer]

Thank you that was such a useful and overall conclusive advice, one of those I will keep with me for a long long time It is a very lovely stone, and ring. I am currently testing it for at friend at my jewelery class. The only purpouse was to concluded whether or not it was natural or not. I will post some pictures here in a minute of the ring.

 

[Procer]

And as promised pictures:

 

[LD]

Procer - what size is that stone? One thing also of note is that you very rarely find round cut alex (especially in larger stones). Unfortunately, you can't tell anything from the photos but it was interesting to see what we've been discussing!

 

[Procer]

I just wanted to demonstrate some of the colors the stones have, but you are right The photos doesn't tell allot, the exact tones and hues of colors are not at all captured. Sometimes the stone is one solid color, other times it is solid with rays of other colors. Very fascinating stone and the first alexandrite I saw in my life, that it turned out not to be a 100% alex is not important.

My friend says that she got it from an relative and that it is sort of an heirloom. The stone is 0.2 inches or 7mm across. And why isn't alex cut round? Has is something to do with its cleavage?

 

[LD]

It's very interesting that your friend says that she got this from a relative. This is such a common story with "alex" rings! Believe it or not, simulants and synthetics have been around for about 100 years or so and unfortunately I can't tell you the number of times I've heard about or seen an "heirloom" that is purportedly an alex and ............ it's not!

Alex is nearly always cut for weight retention because it's such a valuable material and so you very very very rarely see a precision cut stone. In fact, I've never seen one. I've seen well cut stones but not precision cut. For that reason, typical cuts are ovals, pears and cushions. Round cuts are fairly rare in very good material and a decent size and therefore command a premium - even when you do see them, they tend to be wonky rounds!!! You can find rounds in smaller sizes but not in bigger. A 7mm round is about 2ct (if it were an Alex). So if you needed another indication that all may not be what it seems with your friends ring, I would think this is another "worry bubble".