Zoning and/or fluorescence in sapphire - treated/synthetic/natural?

[ringo865]

I have had this sapphire ring for 25ish years. Lately I've been louping it and notice a zone of color that I never noticed in face up viewing.

Here you can see a bit of the zoning.


Easier to see The zoning thru the pavilion. Then some straight bands (not curved) are apparent in macro


So then I wondered if i could determine if it was lab or heated. I was reading about fluorescence in sapphires and learned that at synthetic sapphires would fluoresce and heated ones would have chalky fluorescence. So out came my uv light to see it glow.

And it doesn't glow. Am I missing some obvious fluorescence or chalky fluorescence?

What is the color blob? Could it be heated? Lab? Natural?

 

[Nosean]

First, fluorescence is only an additional diagnostic feature. Never enough to say whether heated, natural, synthetic or otherwise treated.

From the pics I think it is not synthetic and impossible to say whether heated or not.

You find zoning ( growth pattern) in almost every natural sapphire using an immersion microscope wirh the right orientation of the stone. Sometimes you see it with a loupe or naked eye.

You will find typical pattern in some kind of synthetic corundum too.

 

[ringo865]

Thank you Nosean. I guess more microscopic and spectroscopic testing is required. I have been thinking of having it reset. Into what I do not know. The stone is pretty dark, but I do like the blue flashes. I seriously had never noticed the "ink blob" or nearly clear areas in the years I've had it. Only recently, with loupe, macro lens, uv light, and google, have I become a dangerously inquisitive gemophile.

Interesting to note (or maybe not) that every stone I own resembling a ruby - from known natural/heat only, to "maybe" natural, "maybe" created, to totally fake (possibly even glass) - fluoresces like mad.

If only I had all the cool tools

 

[Nosean]

The tools are cheap and easy to use.

A friend of had a waterworn crystal - colorless with six thin blue patches on the upper pyramid. Really nice...

 

[ringo865]

Tell me more about these cheap, easy-to-use tools. I'm in!

 

[ringo865]

@Nosean, I would love to know what (cheap/easy/effective) tools I could get. As an amateur hobbyist, of course.

Microscope? 40x?

Presidium?

 

[Nosean]

Refractometer, Polariscope with Conoscope, Dicroscope, Neodym magnet, some loupes ( 10x, 15x, 20x), Chelsea filter, LW UV, tweezer.

A good scale ( Tanita ) and maybe additional a set to measure density.

 

[ringo865]

Oooh thank you!!! I found a toolkit on Amazon that contains most of these items. I'm about to be dangerous!

 

[pwsg07]

Refractometer, Polariscope with Conoscope, Dicroscope, Neodym magnet, some loupes ( 10x, 15x, 20x), Chelsea filter, LW UV, tweezer.

A good scale ( Tanita ) and maybe additional a set to measure density.

How to measure the SG at home? I don't have those $1000 scale. I have a scale that can measure the carat weight.

 

[Nosean]

Depends on the size off the stone. you weight in water and air.

For Tanita scales and the cheaper chinese ones ( work fine ) there is a kit but for example a small stone ( 0,50 ct - 2 ct ) is is a challenge.

No bubbles in the water and on the stone!!

A 1 ct sapphire with a density of 4 will weight only 0,25 ct in water...

1 ct in air and 0,23 ct in water will be a density of 4,35 - so really misleading!! You have to do it several times with a known material and get practice...

 

[arglthesheep]

@pwsg07 there are many cool instructions in the net on how to build an easy and cheap SG-scale.
Easy explained: you just weight the stone in air normal on the scale, then put a small vessel with water on the scale. Tara the weight to 0. Then weigh the stone in water and use the formula. To weigh the stone in water a small wireconstrution is helpful. But have in mind, that the smaller the stone is the bigger is the deviation from measurements. So normally this works fine for stones bigger then 1 ct...

 

[Nosean]

Yes, works in larger ones....

Small stones are the problem...

 

[pwsg07]

Thank you Nosean and arglthesheep.

 

[Stone Hunter]

Cool project! Good luck figuring it out. Perhaps a trip to a local jeweler that has a refractometer?

 

[T L]

Synthetic sapphires are typically "perfect " and do not show zoning. Zoning is pretty typical of a natural sapphire. Blue sapphire is colored by iron typically which is a fluorescence killer. I've seen synthetic and natural gems fluoresce, so that's not an indication of natural vs. synthetic. However a gemologist can easily determine if it's natural, diffusion treatment is another story.