Heat treated sapphires?

[Pandora II]

There are many forms of heat used - the art of treating gemstones has been going on since at least Roman times, and the burners and cookers in Thailand are experts at it.

Stones can be heated as much as 7 times before the final result is achieved. Temperatures can be as low as 700 degrees C to improve colour - at this temperature many of the natural inclusions and indicators of heat treatment will not be damaged. Around 1400 degrees, rutile silk starts to dissolve and will leave tell-tale signs. Temps can then go up as high as just below melting point - used in this case to diffuse elements into the actual crystal structure.

By using certain times, temperatures and environments as well as cooling/heating fast or slow you can produce all sorts of effects.

Heat-treatment of sapphires makes up the content of some very hefty books!

Honestly, heat treatment is a brilliant invention - it can make an amazing difference to stones and mean that there is far more choice available on the market as well as providing a huge number of people across the globe with their livelihood.

But, you don't want to pay the same price for heated as unheated - ALL OTHER THINGS BEING EQUAL. Ditto for diffusion.

A gemmologist will be able to spot the changes to inclusions that indicate whether a stone has been unheated, low heat, high heat, charred to a cinder etc - many dealers are also gemmologists and/or are using sources that they may have used for many years and who have good reputations. That is as good a guarantee that you will get without a lab report.

There are a lot of labs out in Thailand - AIGS, Tokyo Gem Lab, GIT etc etc, often stones will come with a mini-certificate from one of these. Some are more highly regarded that others - often it depends on the day of the week or who you speak to as to who is in and out of favour.

My personal take is that if it says unheated and I'm paying the premium then I 'may' want a more prestigious report if it's a very expensive stone, if it says low heat then I'm happy, anything else and I probably wouldn't buy it anyway... at £220GBP a report plus the hassle of sending the stone overseas/using drop shippers etc, I have to REALLY need that info to be deal with the hassle!

 

[Chicago Girl]

Honestly, if you love it I would just buy it.

It's kind of coming down to this! I still have plenty of time (my wedding is not until November) but unless I find an all diamond band that i like better, I may just bite the bullet and get a sapphire/diamond melee because I do love the way it looks. Sigh.

plus some Madagascan blue sapphires naturally contain Beryllium so false positives are a potential risk

So Be in and of itself in a sapphire isn't the problem, it's the artificial nature of Be diffusion that's the problem?

I am afraid that when it comes to small sapphire melees in the band, just assume that they are heat treated no matter what at the very least. Just make sure the stones are nice looking (no obvious clarity issues and the colour isn't too dark). There are very few stones in your band (6 or thereabouts, correct) and they are very small. In the overall cost, the diamond melees and metal cost are probably the bulk of the price you paid. In terms of pricing, very few B&M stores can compete with online vendors (although some online vendors do have a front store customers can visit).

As with any vendor, you are going to have to rely on trust when it comes to melee stones. It just isn't cost effective to send such tiny stones to the lab for verification. You will face the same issues of any stone being a synthetic when looking at antique sapphire rings.

All of that makes sense to me. I definitely understand the sapphire melees will be heat treated. I guess whether they're be diffused is another story. If I were purchasing a large sapphire as a center stone, I believe I would be stricter in terms of what types of treatments I would accept. And yes, I think there are maybe 6-8 sapphires in the band (I can't remember from when I viewed the band in person).

Overall, you guys have been SO helpful in educating me about sapphires and making me aware of what I should be on the lookout for, and I really appreciate it.

 

[Chicago Girl]

True, I forgot about synthetics back then. You would hope with a fine art deco piece, it would be natural. *sigh* - just so many issues with sapphires.

Never in a million years would I have thought there were all these issues with sapphires. I know several girls with sapphire engagement rings - I wonder if they are aware of all of these potential issues?! Also, has this been discussed before on PS - was Princess Diana's sapphire ring treated?!!

 

[Chicago Girl]

All, I have some more information from the jeweler, please see below:

*They "guarantee" the sapphires are only heat treated and not subject to Be diffusion (I specifically told them Be diffusion was a concern). They don't provide a certificate but said they can get one if I pay the fee of getting the cert. If it comes back showing treatments other than just heat, then I get a full refund.

The approximate tcw of the diamonds on a size 4 band is .3 carats.

If I got the same band but with all diamonds and no sapphires, it would be 3800. The price with diamonds/sapphires is 3250.

Let me know what yall think.

 

[T L]

True, I forgot about synthetics back then. You would hope with a fine art deco piece, it would be natural. *sigh* - just so many issues with sapphires.

Never in a million years would I have thought there were all these issues with sapphires. I know several girls with sapphire engagement rings - I wonder if they are aware of all of these potential issues?! Also, has this been discussed before on PS - was Princess Diana's sapphire ring treated?!!

Your friends probably have no idea about their sapphires treatments. I would assume they're all heated, and if they're lucky, not diffused. I don't know if Princess Diana's stone was treated, but I would assume heat. I never heard otherwise. I don't even know the origin of her stone, but I heard Australia once (not sure if that's true).

Unfortunately, sapphires are ultra-marketed to the public, and a great way for a jeweler to make a huge profit because they aren't forced to disclose treatment if not asked.

 

[T L]

All, I have some more information from the jeweler, please see below:

*They "guarantee" the sapphires are only heat treated and not subject to Be diffusion (I specifically told them Be diffusion was a concern). They don't provide a certificate but said they can get one if I pay the fee of getting the cert. If it comes back showing treatments other than just heat, then I get a full refund.

The approximate tcw of the diamonds on a size 4 band is .3 carats.

If I got the same band but with all diamonds and no sapphires, it would be 3800. The price with diamonds/sapphires is 3250.

Let me know what yall think.

#1) Where do they get the certificate? If "in house," I wouldn't trust it. If the stones are diffused, the lab report can also just say heated, and not tested for foreign elements, so you still lose out not knowing the full truth unless you remove the stones and have them tested by some expensive machine. Sometimes you cannot tell if a sapphire has been diffused via diagnostic evaluation. The machine they use to test for diffusion is very expensive, and not all labs have access to one.

#2) I don't think it's worth it to pay for a lab report for the GIA, AGL, or other reputable lab for just 0.3 cttw of melee.

#3) If it really bugs you that they might be diffused, then skip getting sapphire melee (or any corundum or rubies) at all.

 

[Pandora II]

Diana's sapphire was from Sri Lanka aka Ceylon. IIRC it was heated.

 

[T L]

Diana's sapphire was from Sri Lanka aka Ceylon. IIRC it was heated.

Thanks Pandora, it does look Australian though (and I don't mean that as a compliment!! )

I can only imagine what it looked like before it was heated.