Red Sapphire

[Richard M.]

Hi,

I have a question for the corundum experts here. For several years I''ve been seeing red corundum principally from Songea, Tanzania marketed as "red sapphire." The color of the material reminds me of Thai ruby with its characteristic garnet-like iron coloration. But Thai material is sold as ruby, not sapphire. So what''s going on here? Does Thai material have enough chromium content (if that''s the defining standard) to qualify it as ruby with chromium being absent in the African goods? Help, my head is spinning! Gem terminology is messed up enough already without this complication.

Richard M.

 

[valeria101]

One answer from GRS says, yes, all contain Cr.

Gem&Gemology (Summer 2000 and others) reffer to reddish corundum from Malawy, and Tuduru-Songea as "chromium bearing" off the bat...

Is there any study saying the opposite? The association with Cr vs Vd in emerald is tempting, but... never heard of "African ruby" as anything but a tradename meant to give these gems a more forgiving refference group than "ruby" fullstop

 

[Richard M.]

I''ve always been told that when corundum is red it''s called ruby. The question of chromium content is not really central to my question -- I raised it only as a possible explanation of why some of the red Songea material is called sapphire. I don''t believe the material I have in mind is Be-diffused.

Here''s an example of what I mean: Red Sapphire

The seller says the stone is heated, not Be diffused. I have no idea how scrupulous this particular seller may be about disclosing all treatments.

I''ve run across a number of other sellers describing red African corundum as sapphire, not ruby. Yet many sources mention Songea and numerous other African locations like Tunduru and Longido as sources for ruby and I''m wondering about the terminology.

 

[Mayacamas]

It has been my observation that stones that are being sold as red sapphires are generally Beryillim treated sapphires to get the red color, as opposed to heat treated rubies to make them more intense red.

Just an observation.

 

[Richard M.]

Date: 12/5/2004 1:39:40 PM
Author: Mayacamas
It has been my observation that stones that are being sold as red sapphires are generally Beryillim treated sapphires to get the red color, as opposed to heat treated rubies to make them more intense red.

Could be, but I bought parcels of Songea rough, said to be unheated, as long ago as 1996 or ''97 that contained ''red sapphires'' along with the usual blue-greens and pastel yellows, peaches, mauves, purples, color-shifters, etc. They were dark garnety reds, not the brighter more orangy reds of the Be diffused Songea corundums. Maybe the Be process was secretly being used that long ago but these roughs were relatively small and seemingly not important enough for such treatment. I''ve also purchased similar-appearing material sold as "African ruby." Heat was used to drive off an undesirable blue color, as with Burmese Mong Hsu corundum. Maybe I''m totally off base with this and if so I''m sure Richard Hughes or Vincent will straighten me out.

 

[imperial Jewels]

Its probably Be-treated songea sapphire. Frequent tell tales signs are the dark blue spots that the Be-process creates from Titanium Oxide crystals.

 

[Sasori]

Hi Simon!
Haven heard from you about my blue melees yet..

Ryan

 

[mogok]

Hello,
Red gem variety of mineral corundum is called ruby. All other varieties are called "sapphire".
Ruby is more expensive than sapphire... At AIGS lab many companies send us some borderline stones between purple and red, or orange and red hoing that they will get a report with "orangy red ruby" or "purplish red ruby", if we issue the word sapphire they are not that happy... and I understand this.
So why should people call a stone a red sapphire? Think about it...

There is just no common sense to that... except in the case of something hidden as "red sapphire" is better selling name that "bulk or lattice diifusion songea sapphire" (which names are not really in my favor I have to say very franckly...). I think that many mistakes were done in this story and when I look at the stones I think that Thais are may be wonderful alchemists but so bad marketing people. Such a nice product would have had a great success if it had been in the hand of powerful companies like Swarovky selling lead-glass to the world under the name of "crystal". But it was not the case... Greed and ignorance are the 2 devils within the gem trade.

To come back on the subject, GRS lab in Bangkok was at the very beginning involve in the controversy with the beryllium story. They have decide to issue reports with the mention "red sapphire" for stones from Songea that were heated with the beryllium technology in order to reflect (I think...) that these stones were not born as rubies but as sapphires. Then a treatment gave them some color that some people could agree for ruby. Most of these stones are usually too orange to be called rubies but some present a pleasant bright orangy red.

You can see the before and after on the following photos:

Before heat treatment they are obviously not rubies:

After treatment with beryllium well some areas can be subject to discussion:

The difference is even more obvious if you consider observation under immersion (which is excellent to observe color zoning):

Songea sapphire before treatment:

Now the same stone after treatment with beryllium:

You can find several information on this subject on internet. I''ve written a small article about it for a french website: geminterest.com
"Histoires et realites" autour du traitement dit "au beryllium" (in french sorry...)

Now you can also find some information about it on the excellent articles from Richard Hugues:
walking the line in ruby & sapphire
the skin game

Some info are also visible on GRS website:
GRS contribution to gemmology vol 1
GRS contribution to gemmology vol2

There are also several other places to find some info as GIA, AGTA websites and much more...

All the best,

 

[Richard M.]

Thanks, Vincent, for this information. Can you tell me approximately how long such diffused stones have been on the market? As I mentioned in earlier posts I was purchasing a few red Songea corundums -- in the rough -- as long ago as 1995-96. The stones were small, maybe .80-1.25 ct. before cutting.

The color of my material is much darker than most of the Be-diffused reds I''ve seen, which as you say tend to be "orangy." As I mentioned earlier it reminds me of iron-rich Thai ruby or pyrope-almandine garnet.

I certainly agree that calling red corundum "red sapphire" sets off all sorts of alarm bells and that''s why I''m pursuing this. I thought the red Songeas I was seeing predated the Be treatment but possibly not.

Richard M.

 

[mogok]

In 95-96 there was no beryllium treatment...
It was discovered around 2000.
All the best,

 

[rubydick]

I would echo the excellent comments of Vincent.

In 1997-98 I saw a number of these Songea "rubies." Stones were red, but with strong orangy overtones. These stones were certainly more red than orange, and thus ruby to me, but some would call them sapphire.

They appeared to be of magmatic origin, and were extremely rich in iron, to the point where some showed a combination Fe-Cr spectrum.

Since late 2001, I''ve also seen the beryllium-treated stones. These have been peddled on home shopping networks. One of the names used for them is "ratnaraj" ruby. Gotta give somebody credit for that creative label.

These stones showed a red color more like red spinel than ruby, and with immersion, showed orange rims. All other features were like Songea stones.