Why is there no green star sapphire?

[pokerface]

Green's a common enough color, and asterism is not a rare phenomenon, yet I have never seen the two occur simultaneously. Is there a reason why green and asterism cannot coexist in a sapphire? I have been looking for over a decade, and I see no evidence of even a low-quality green star sapphire. Please enlighten me, or prove me wrong!

 

[chrono]

You are absolutely correct observing that yellow, orange and green star sapphires are especially rare. I'm not sure why the crystal growth doesn't support creating/alignment of the star pattern for these colours. I also don't think that green sapphires are particularly plentiful either.

 

[voce]

@Bluegemz I didn't see a website but saw this up on Instagram: https://www.instagram.com/p/BfawYFCnrxJ/?taken-at=317185665378911

Another one:
https://www.instagram.com/p/BfpfEi5HVeG/?hl=en&taken-at=1032004137

They exist, but probably out of my price range.

 

[pokerface]

I question both of those examples. In the first, the star is clearly photoshopped. The second looks like a Lindy star, or synthetic sapphire + photoshop.

 

[voce]

You're entitled to your opinion. This shop is a brick and mortar shop in Hong Kong, and they've sold a lot of expensive jewelry.

 

[pokerface]

Yup, well, I'll believe it when I see the lab report. What are the chances that a single dealer has two fake-looking gems (that are actually real and valuable), and no other vendor in the world has any? On the first example, you can actually see green around the edges where the photo has been photoshopped. Not to mention that if you google, "green star sapphire," you will see that your brick and mortar shop has taken (stolen?) the first photo and altered it to be brighter green. Grand Mantra Ploy

First result when you google "green star sapphire"

 

[voce]

Okay, after looking further into this, I am convinced that you are right. Green stars must be synthetics.

The reason why green and yellow star sapphires are rare is due to the lack of titanium. Trace elements of both iron and titanium cause blue coloration, chromium causes red or pink, orange and pad require both iron and chromium, and purple comes from vanadium. For green and yellow coloration the trace element is predominantly iron without titanium.

It seems for the other colors of sapphire, some titanium can be present without influencing the sapphire's primary color, e.g. red/pink, purple, and padparadscha, I think. But if titanium were present in green or yellow, then the result would be bicolor or parti, if not blue.

Asterism in sapphire is caused by silk rutile inclusions, which have a chemical composition of titanium dioxide.

So, a green or yellow star sapphire must form their crystal in a titanium poor environment, yet somehow still have some titanium dioxide inclusions. Sounds rather unlikely, right?

Sources: https://www.thenaturalsapphirecompa...n-corundum-can-create-one-of-a-kind-sapphires

https://en.m.wikipedia.org/wiki/Asterism_(gemology)

 

[LemonMoonLex]

I found some greenish-blue and yellowish-green star sapphires on ebay that are totally natural albeit very low quality. They were actually pretty easy to find.

https://www.ebay.com/itm/STAR-SAPPH...205187?hash=item2ce443bb83:g:yx4AAOSwCA5bYorJ

https://www.ebay.com/itm/ANTIQUE-CABOCHON-8-40-CT-STAR-GEMS-ONLINE-BLUE-GREEN-SAPPHIRE/273647624154?_trkparms=aid=111001&algo=REC.SEED&ao=1&asc=20160908105057&meid=a6c3dfc474fa483da835684c92425cfa&pid=100675&rk=1&rkt=15&sd=273647624154&itm=273647624154&_trksid=p2481888.c100675.m4236&_trkparms=pageci:8046ad41-2716-11e9-8651-74dbd180edda|parentrq:af6c0d281680ab4dd5014143ffdd320f|iid:1

 

[icy_jade]

I saw this on ig recently

 

[AZBRISBANE]

Hi Guys. Realise this is an old thread but just letting you know that there are green star sapphires in Australia but are also extemely rare here. I have several stones and they came from a place near Emerald in central Queensland. They are a dark green stone and i have had them certified by a recognised valuer. In her 50yrs in the industry, she has heard of them but never seen them before. One reason for the rarity is that the lease that they came from may have been shut down due to environmental issues. My stones were mined and cut in the 1970's. I managed to buy the entire collection from a deceased estate. They are really something different and mesmerising. They have been tested and confirmed that no heat treatment has been done. Unfortunately...i wont be selling any of them but I do know there is only another one in existence that I know of and it is larger than any one of the ones i have.

 

[pokerface]

Pics??

Hi Guys. Realise this is an old thread but just letting you know that there are green star sapphires in Australia but are also extemely rare here. I have several stones and they came from a place near Emerald in central Queensland. They are a dark green stone and i have had them certified by a recognised valuer. In her 50yrs in the industry, she has heard of them but never seen them before. One reason for the rarity is that the lease that they came from may have been shut down due to environmental issues. My stones were mined and cut in the 1970's. I managed to buy the entire collection from a deceased estate. They are really something different and mesmerising. They have been tested and confirmed that no heat treatment has been done. Unfortunately...i wont be selling any of them but I do know there is only another one in existence that I know of and it is larger than any one of the ones i have.

 

[AZBRISBANE]

First photo is a stone sitting on top of the phone flashlight.

2nd photo is taken using the phone and flash on.

 

[pokerface]

The first photo is pretty terrible and the stones look gray in the second photo. Do they look greener without flash? I did find one example available on Etsy but ultimately decided that the green is too dark for my taste.

 

[LemonMoonLex]

First photo is a stone sitting on top of the phone flashlight.

2nd photo is taken using the phone and flash on.

The second photo looks like regular black star sapphires to me. Also black star sapphires when shown a light through them can look yellow or green, that doesn't make them green though.

 

[Starstruck8]

Here's one:

Continuing the theme of greenish sapphires... Here's an olive green star sapphire I'm considering!

This looks so interesting (albeit far from perfect for a star sapphire?) and I've never seen a natural green star sapphire before, so...
Calling all the star connoisseurs!

Olive-y, certainly, but definitely green.

This tiny one is mine:

Grey-blue-green, but I think it counts as green. It comes from Central Queensland.

Surely the same source as this:

Hi Guys. Realise this is an old thread but just letting you know that there are green star sapphires in Australia but are also extemely rare here. I have several stones and they came from a place near Emerald in central Queensland. They are a dark green stone and i have had them certified by a recognised valuer. In her 50yrs in the industry, she has heard of them but never seen them before. One reason for the rarity is that the lease that they came from may have been shut down due to environmental issues. My stones were mined and cut in the 1970's. I managed to buy the entire collection from a deceased estate. They are really something different and mesmerising. They have been tested and confirmed that no heat treatment has been done. Unfortunately...i wont be selling any of them but I do know there is only another one in existence that I know of and it is larger than any one of the ones i have.

The second photo looks like regular black star sapphires to me. Also black star sapphires when shown a light through them can look yellow or green, that doesn't make them green though.

Mine's not a typical black star sapphire, nor are these. The zoning (visible in the lower stone in the 2nd pic) is at 30 degrees to the long ray. Same for the zoning in mine. This is typical of 'normal' (rutile) stars. In typical black star sapphires, the star is formed by ?hematite, and the zoning is parallel or at 60 degrees to the long ray.