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!