Demantoid vs green zircon

[Double E]

Two varieties known for similar (not exact) attributes such as colour and dispersion, how different are their actual performance?

 

[chrono]

I have yet to see a green zircon that wows me because those I've seen are too dark. I have seen demantoid comparable in colour and sparkle to chrysoberyl.

 

[fredflintstone]

Depends on tone & cutting.

Green Zircon in a medium tone to light tone well cut with a high crown can be quite stunning, but it is what is called low Zircon in most cases. It does not have as high as refractive index as medium or high Zircon, but it has the same dispersion, and though Zircon is known as doubly refractive, green Zircon many times acts as singularly refractive because of the breakdown of the crystal lattice due to radiation.

All in all, though green Zircon can be quite stunning, it cannot compete with the best Demantoid and the price reflects that.

 

[Double E]

Well cut clean hue chryso can be quite sparkly. But dispersion May be something chryso is lacking compared to the other two.

However, how obvious is that “fire” on demantoid and green zircon irl? I have an impression that green zircon, especially more vivid and darker ones shows however less fire when compared to say blue zircon. And as demantoid has higher dispersion (I hope I am right here, otherwise just correct me), should it be more firey than green zircon?

 

[Double E]

For high vs low zircon, is colour saturation still the core criteria, eg more vivid means higher, similar to many other gems? I am curious how a vivid green zircon performs, but having seen one.

 

[T L]

Your typical green zircon cannot compete with the fire of a demantoid, but I once saw a very pale green zircon from the famed Cambodian blue zircon mines, and it was amazing. I’ve never seen one since.

 

[musicloveranthony]

I have a really beautiful green zircon from Sri Lanka. It's cut in a triangle shape. It sparkles fantastically. Demantoid has a higher amount of dispersion than zircon but it is classically an included stone. Russian demantoid especially is known for its inclusions. Namibian demantoid tends to be cleaner and lighter in tone - so higher visible dispersion. You can find clean demantoid from Namibia, but it has a lighter tone than the classic Russian stones - so it isn't as vivid; it's more of a yellow and/or brown tinged.

Clarity for clarity and tone for tone demantoid will be higher in fire than demantoid, because science.

I'm at work today, but later this weekend I'll try to get a photo and video of my pure green, clean zircon next to a Mali garnet I have that is extremely high in dispersion.

 

[fredflintstone]

Well cut clean hue chryso can be quite sparkly. But dispersion May be something chryso is lacking compared to the other two.

However, how obvious is that “fire” on demantoid and green zircon irl? I have an impression that green zircon, especially more vivid and darker ones shows however less fire when compared to say blue zircon. And as demantoid has higher dispersion (I hope I am right here, otherwise just correct me), should it be more firey than green zircon?

The lighter toned color on green Zircon if it is well cut can show a lot of dispersion, plus the lighter greens can be medium Zircon, even high in some cases.

Very green Zircons in a medium tone with none of the typical haziness associated with green Zircon can be quite brilliant. Haziness is another factor to consider when looking for a dispersive green Zircon.

Blue Zircon is high Zircon and doubly refractive, hence you get back what seems twice the dispersion. Though, very seldom is blue Zircon as vivid as the best green Zircon, which can hide dispersion somewhat.

Funny enough it is yellow Zircon & Imperial Zircon that shows the best dispersion, and some Imperial Zircon can be fairly dark in tone. Both are high Zircon.

 

[musicloveranthony]

The lighter toned color on green Zircon if it is well cut can show a lot of dispersion, plus the lighter greens can be medium Zircon, even high in some cases.

The Sri Lanka green zircon I have is light to medium in tone (it's got a blue-green hue), but is definitely high zircon. No eye visible inclusions - I will have to loupe it for when I take pics/vids for this thread. Definitely no haze, either.

Most of the clean looking green zircon I've seen is dark enough in tone that I don't expect they'd show much in the way of dispersion. They also seem to have an "oil in water" effect that I don't know the gemological term for (not double refraction; it's a different effect)

 

[fredflintstone]

The Sri Lanka green zircon I have is light to medium in tone (it's got a blue-green hue), but is definitely high zircon. No eye visible inclusions - I will have to loupe it for when I take pics/vids for this thread. Definitely no haze, either.

Most of the clean looking green zircon I've seen is dark enough in tone that I don't expect they'd show much in the way of dispersion. They also seem to have an "oil in water" effect that I don't know the gemological term for (not double refraction; it's a different effect)

If it has highly visible double refraction, then yes, it is high Zircon, but medium Zircon has pronounced double refraction too.

Very rare (next to nonexistence) for a medium tone green to be high Zircon. If there is blue in it, then it has probably been heated to turn into a blue Zircon, but not all heat blue all the way, as matter of fact most have some green in them. But some have a lot of green.


Please do share.

 

[musicloveranthony]

If it has highly visible double refraction, then yes, it is high Zircon, but medium Zircon has pronounced double refraction too.

Very rare (next to nonexistence) for a medium tone green to be high Zircon. If there is blue in it, then it has probably been heated to turn into a blue Zircon, but not all heat blue all the way, as matter of fact most have some green in them. But some have a lot of green.


Please do share.

Yes, i'm confident it was heated and supposed to turn blue but didn't quite make it there

 

[Double E]

How about a vivid green zircon with a medium tone, eyeclean and without metamoct dimness? How should we rate such stone?

I am a bit confused for the criteria to determine whether a zircon is high or low or anywhere between the two…Is remaining double refractive a one of the key requirements? This seems what I got from our discussion so far.

 

[Mreader]

I have a really beautiful green zircon from Sri Lanka. It's cut in a triangle shape. It sparkles fantastically. Demantoid has a higher amount of dispersion than zircon but it is classically an included stone. Russian demantoid especially is known for its inclusions. Namibian demantoid tends to be cleaner and lighter in tone - so higher visible dispersion. You can find clean demantoid from Namibia, but it has a lighter tone than the classic Russian stones - so it isn't as vivid; it's more of a yellow and/or brown tinged.

Clarity for clarity and tone for tone demantoid will be higher in fire than demantoid, because science.

I'm at work today, but later this weekend I'll try to get a photo and video of my pure green, clean zircon next to a Mali garnet I have that is extremely high in dispersion.

Yes photos please @musicloveranthony !! You have been hiding your collection from us

 

[fredflintstone]

How about a vivid green zircon with a medium tone, eyeclean and without metamoct dimness? How should we rate such stone?

I am a bit confused for the criteria to determine whether a zircon is high or low or anywhere between the two…Is remaining double refractive a one of the key requirements? This seems what I got from our discussion so far.

I had many medium tone vivid green Zircons in the day, eye clean, without the haze, but they are still metamict = low Zircon. There are no non-metamict medium tone green Zircons. Just ones that are not as far down the road of crystal lattice breakdown as others.

As I wrote, the radiation breaks down the crystal lattice. This takes millions of years. It turns the Zircon into basically amorphous glass (harder to polish) with a hardiness of 6 1/2, like Tanzanite and Peridot. Not the usual 7 1/2 hardiness. It loses its double refraction and becomes singular. While it still has the dispersion of normal Zircon (high, medium) the vivid color masks it more, as does the single refractiveness because it is not shooting back light at you in two rays, only one. So, it will not seem as dispersive as high or medium Zircon.

All this said, they are still beautiful stones. When cut well with a high crown will give you great light return and some dispersion, albeit not as much as high Zircon. I would not discourage anyone who is really interested in buying one not too. They are rare and normally more expensive than all other Zircon with only the best blues rivaling them in price.

Want to learn more?

Zircon Description

Zircon occurs in an array of colors. Its wide and varied palette of yellow, green, red, reddish brown, and blue hues makes it a favorite among collectors as well as informed consumers.

www.gia.edu

 

[T L]

Namibian demantoid elongated cushion next to a round green zircon. The demantoid has fire, the zircon doesn’t. The demantoid has a slight bluish tint but the zircon is slightly yellowish, but both are primarily green. Some demantoid are yellowish green. Bad photo, sorry. The zircon darkens up in natural light. I prefer the demantoid by far. The zircon is very brilliant in artificial light, which is this photo.

 

[T L]

Two green zircon.

 

[NexivRed]

No advice on a zircon, but here is my Russian demantoid on an overcast day, flash under artificial light and flash indoors on overcast day; no light.
The fire on this thing is amazing.

 

[landscape]

VV green zircon has the same color performance as demantoid, but the dispersion effect is different, demantoid has fire, but green zircon has almost no fire.
Below are green zircon，The round zircon color is VV green.
I will take pictures of zircon vs demantoid in my spare time later