Question about Ruby heating and residues

[Mreader]

I have noticed just anecdotally from searching GIA certed rubies, that heated rubies from Burma often have residues. When I have come across those from Thailand, the reports just say “heated”. I haven’t come across a heated Thai Ruby that says residues.

Is this just a fluke and there are Thai rubies w residue, or is there some reason for why heated Thai rubies might not leave behind residue?

 

[Avondale]

If a stone isn't fractured, then there's no need to heat it with borax in order to stabilise it.

But considering Thailand is more or less the birth place of flux heating, I very much doubt no Thai rubies get subjected to it. I'd guess it's just a matter of which stones you stumble upon.

 

[VividRed]

The vast majority (>90%?) of Burmese rubies come from Mong Hsu, not Mogok. Mong Hsu rubies are, for the most past, heavily fractured. Fracture healing through high temperature heating with added borax is necessary to bring them to market.

Other localities such as Thailand, Mozambique, and Madagascar are much less affected, hence the *relative* lack of fissure healed rubies.

 

[Mreader]

The vast majority (>90%?) of Burmese rubies come from Mong Hsu, not Mogok. Mong Hsu rubies are, for the most past, heavily fractured. Fracture healing through high temperature heating with added borax is necessary to bring them to market.

Other localities such as Thailand, Mozambique, and Madagascar are much less affected, hence the *relative* lack of fissure healed rubies.

That makes so much sense - thank you!

 

[Autumn in New England]

Keep us posted, @Mreader!

 

[Dr_Diesel]

The vast majority (>90%?) of Burmese rubies come from Mong Hsu, not Mogok. Mong Hsu rubies are, for the most past, heavily fractured. Fracture healing through high temperature heating with added borax is necessary to bring them to market.

Other localities such as Thailand, Mozambique, and Madagascar are much less affected, hence the *relative* lack of fissure healed rubies.

My understanding is that that most African rubies are heated in Africa and that is done without Borax.

I also understand that essentially all Thai and Burmese rubies are heated in Thailand. A friend and former Mong Hsu ruby miner told me that they don't do any heating at all in Myanmar. They just sell the rough to Thais and let them sort it out.

My understanding is that, In Thailand, most rubies are batch treated and thus preemptively heated with borax, no?

I'm not sure I've ever seen a Thai ruby that was heated without borax. African rubies, yes. Thai and Burmese, no.

Of course, Thai rubies are less common, so I'm pulling from a relatively limited sample size - and it's based entirely on personal experience.

 

[qubitasaurus]

I have noticed just anecdotally from searching GIA certed rubies, that heated rubies from Burma often have residues. When I have come across those from Thailand, the reports just say “heated”. I haven’t come across a heated Thai Ruby that says residues.

Is this just a fluke and there are Thai rubies w residue, or is there some reason for why heated Thai rubies might not leave behind residue?

This is probably because several labs like gia don't say residues they just say heat H(a) or another nomenclature -- it means heated with borax so they've definitely got flux healing.

 

[Mreader]

This is probably because several labs like gia don't say residues they just say heat H(a) or another nomenclature -- it means heated with borax so they've definitely got flux healing.

Well, actually, the reports that I’ve been looking at have been GIA and I’ve noticed they say either heated or minor or moderate residue. And I’ve just noticed that ones from Burma tend to show the residue and then others like Thailand, etc. say heated, which is why the explanation about the fracturing from Burma makes so much sense.

 

[Dr_Diesel]

Well, actually, the reports that I’ve been looking at have been GIA and I’ve noticed they say either heated or minor or moderate residue. And I’ve just noticed that ones from Burma tend to show the residue and then others like Thailand, etc. say heated, which is why the explanation about the fracturing from Burma makes so much sense.

It’s possible that many of the Thai rubies you are seeing were mined & cut before the 1990s when borax heating became mainstream.

The 1970s and 1980s were kind of the heyday for Thai Ruby production and most of the Thai and Cambodian mines were exhausted my the mid 1990s

It stands to reason that there were a few years of crossover where we were seeing Thai rubies heated with borax, but most of them were likely mind prior to that era.

 

[qubitasaurus]

Well, actually, the reports that I’ve been looking at have been GIA and I’ve noticed they say either heated or minor or moderate residue. And I’ve just noticed that ones from Burma tend to show the residue and then others like Thailand, etc. say heated, which is why the explanation about the fracturing from Burma makes so much sense.

Actually I've been looking for the information and I also am seeing Heated as a standard grading not H(a) on gia lab reports -- Im a bit tired due to work deadlines so my memory is not 100% reliable at the moment and I am beginning to wonder if I confused them with grs which does use this nomeclature

Gemstone Enhancement Disclosure -

Understand the different terminology for gemstone treatments and enhancements found in our GRS Reports

www.gemresearch.ch

 

[Avondale]

Actually I've been looking for the information and I also am seeing Heated as a standard grading not H(a) on gia lab reports -- Im a bit tired due to work deadlines so my memory is not 100% reliable at the moment and I am beginning to wonder if I confused them with grs which does use this nomeclature

Gemstone Enhancement Disclosure -

Understand the different terminology for gemstone treatments and enhancements found in our GRS Reports

www.gemresearch.ch

GIA doesn’t use the letter designations in parenthesis. Their reports state “heated” and then add, if present, “[degree of] residues”. You’re right, the H(a/b/c/d) thing is from GRS. Although I’m pretty sure other labs use it as well, it’s just that GRS is the most prominent one.