Antique sapphires....heated?

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I should know this, but when did they start enhancing sapphs/rubies with heat?

Lookie at this nineteenth century stunner...35ct sapphire!

Do you suppose it''s heated?

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[Richard M.]

I believe large-scale modern heat treatment of Sri Lankan geuda began in the 1970s in Bangkok. But the heating of gems, including corundum, has a very long history. Treatment expert Ted Themelis cites references to heating ruby and sapphire in the ancient Indian "Puranas" ("Ancient Lore" in Sanskrit). He cites many later references from the llth century onward. Several 19th century comments imply widespread (and long-standing) use of heat.

In his 1892 book "Precious Stones and Gems," prominent London jeweler E.W. Streeter, wrote: "Precious stones are often burnt or subject to a high temperature, the heat exercising a very peculiar influence upon many stones and in some cases modifying or utterly changing their color. The pink Brazilian topaz, too, derives its remarkable color from burning. Rubies are occasionally infected with white spots which can be removed by burning."

Modern gemological techniques for distinguishing heated corundum should be able to establish the treatment history if any of the beautiful stone in question.

 

[chantal990]

Hi,

I was under the impression that heat treatments have been around for centuries and became really mainstream and accepted for rubies and sapphires in the 1960''s (Antionette Matlins - Jewelery and Gems buying guide).

 

[elmo]

One of the trade experts will do a better job explaining the technical details, but I believe that the more modern heating that for example transforms geuda into something pretty isn't the same thing as has been practiced over the longer term. Modern technology allows stones to be brought close to the melting point of the material. At some point I think you have to ask yourself whether the result is any more desirable than a synthetic.

Something else to consider is whether a piece is really an antique or just looks like one. Or if the setting may be antique and the stone replaced. We had once considered a ruby ring with OEC accents like this being sold at auction but our appraiser cautioned that the piece potentially looked too new (mint condition with no signs of restoration) for being 100 years old. For this (and other reasons) we passed on it.

 

[bar01]

Date: 12/17/2004 7:44:57 AM
Author: elmo
At some point I think you have to ask yourself whether the result is any more desirable than a synthetic.

Good point - Here is some interesting information - and they talk about the history of treatments


Articles and Essays on Sapphire Treatment


and of Course the big guy has Something to Say

 

[valeria101]

Now... looking at that thing, who cares? Heat or no heat. It''s still one crazy face - not to mention the frame !

 

[widget]

Thanks, everybody! I KNEW I should know this...

Elmo: the above piece is being offered for sale (for a king''s ransom) by a very tony London antique dealer...www.sjphillips.com... so I''m pretty confident it''s an authentic antique.

Valeria: Amen!!! My two favorite things in the world are beautiful colored gemstones and antique jewelry. When I see a piece that fits both catagories, my knees get weak!

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[valeria101]

Hm... know the place. Some "to die for" stuff - as you guys say:

 

[canuk-gal]

Date: 12/17/2004 11:34:21 AM
Author: widget
My two favorite things in the world are beautiful colored gemstones and antique jewelry. When I see a piece that fits both catagories, my knees get weak!

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HI:

I''m with you here....oh blasphmy...did I say that out loud????

cheers--Sharon

 

[widget]

Valeria...Two questions... Sorry I''m so dense, but I don''t get the ketsup reference...

Second... aren''t you in England? Have you actually ever been IN S.J. Phillips????
Is it mind boggling???

If I ever go to England again, it''s on my list! Who needs to see the Crown Jewels??

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[valeria101]

Date: 12/17/2004 12:10:30 PM
Author: widget

Sorry I''m so dense, but I don''t get the ketchup reference...

I spent a couple of years in the UK, know the shop... But that cultural immersion was nowhere near sufficient to understand
THIS (not the bottle, the sterling top is the showpiece!)

 

[elmo]

Date: 12/17/2004 11:34:21 AM
Author: widget
the above piece is being offered for sale (for a king''s ransom) by a very tony London antique dealer...so I''m pretty confident it''s an authentic antique.

As has been said here before, when it comes to expensive collectibles I think you always must "trust but verify". The biggest names in the business can get hosed by their suppliers, have a temporary lapse, or whatever. That has been our experience.

 

[rubydick]

Heat treatment of corundum is ancient. It is mentioned in the Hindu Puranas (circa 900 BC), but the techniques no doubt were developed prior to that date. Certainly, Arab-languages sources (al-Biruni, al-Teifaschi) were soon after providing much detail on these methods.

But high-temperature treatment of ruby and sapphire is strictly a modern phenomenon. In the late 19th century, furnace technology made possible high-temperature treatments. As this technology drifted towards the producing countries, we find further clues. Australian sapphires were reportedly treated early in the 20th century in Germany. Geuda sapphire treatment became widespread in the mid-1970s. The rest is history.

For more on this, see Chapter 6 of my book:

Ruby & Sapphire

Or this article:

A Brief History of Heat

See also:

Hughes, R.W. (2003) The history and politics of heat. The Guide, Vol. 22, Issue 5, Part 1, Sept.–Oct., pp. 1, 4–9, 15.

 

[mogok]

Hello,
Back from Kanchanaburi were I had an interesting sivit to a sapphire "Burner"!
From Coke furnace (up to 1500c), to diesel ones (1800c) and finally gas furnace (2000c) we had a great vision in the same room of the evolution of technology during the last 30 years this man was performing his alchemical art...
If I prefer for myself unheated gems, I dont mind heat treatment (even using additives like fluxes, beryllium or whatever) as long as the customer is informed about what he is buying...
For the rest a beautiful stone is a beautiful stone!

All the best,

 

[Colored Gemstone Nut]

Date: 12/19/2004 7:46

1 PM
Author: mogok
Hello,
Back from Kanchanaburi were I had an interesting sivit to a sapphire ''Burner''!
From Coke furnace (up to 1500c), to diesel ones (1800c) and finally gas furnace (2000c) we had a great vision in the same room of the evolution of technology during the last 30 years this man was performing his alchemical art...
If I prefer for myself unheated gems, I dont mind heat treatment (even using additives like fluxes, beryllium or whatever) as long as the customer is informed about what he is buying...
For the rest a beautiful stone is a beautiful stone!

All the best,

Interesting Mogok...

Being on site and dealing with many stones there are many nuances described about particular sapphires from different regions. What are some of the distinguishing characteristics you have seen in saphhires coming from Kanchanaburi which help you identify them from this region.

I know a more technical analysis (such as a lab) is for further inspection, but in general what are strong attributes of kanchanaburi sapphires which set them apart from stones in other regions...for example (Ceylon or Burma)