Unheated stones after torching in jewelry setting

[Seaglow]

So many are particular with unheated stones. My preference is unheated as well. Has anyone experienced an unheated stone with a lab report that turned heated after? I've got one but from different labs, but different labs can have different results.

A stone when set can get torched unless there is specific instructions to place the stone without torching. Also when cutting stones, a part can also be torched to soften the wax or epoxy.

If the stone has a liquid inclusion, say in a two or three-phase inclusion, a bit of heat I think can affect especially if the inclusion is close to the surface.

Thoughts, anyone?

 

[crescentgems]

Normally when sapphires are heated to change color they are heated to 900 Degrees celsius to 1850 degrees ( depending on the Process.) , also the time period is around 5 hours to 3 days ( depending on the Process. )

melting point of gold is 1064 Degrees celsius. and also the flame is directed at the metal and time heated may be a few seconds ( just to melt the gold ). BTW melting point of corundum is 2030 degrees

"If the stone has a liquid inclusion, say in a two or three-phase inclusion, a bit of heat I think can affect especially if the inclusion is close to the surface. "

Well the unthinkable can happen , I think mostly if anything happens would be for the rapid heating and cooling of the stone.

Stones like Zircon, Apatite an opal which are heat sensitive have a much more chance of changing due to the setting process

 

[normanintheskywithsapphires]

upto 3 days? Wow. Very interesting. Thanks.

 

[Seaglow]

upto 3 days? Wow. Very interesting. Thanks.

A quote from. Ruby-sapphire.com. Up to 20 days....

In Sarandib [Sri Lanka] and its environs, ruby is treated by fire. People take pebbles from the earth and crush and compress them into a mass with the aid of water. [This mixture] is daubed completely around a dry stone. Then, the whole thing is placed on a rock with other rocks set down around it. Dry firewood is thrown on top, lit and blown upon [with bellows]. The blowing is applied, along with more wood, till any black overtones on the ruby have disappeared.

The amount of fire and the application of wood depends on the extent of the blackness present. People know this by experience. They heat-treat stones for at least one hour and, at most, twenty days and nights. Then, they carefully extract the ruby, its blackness having disappeared.

The ruby is not heat treated a second time. After one treatment, its color can neither improve nor diminish.

Teifaschi, ca. 1240 AD,
into French by Clément-Mullet (n.d., ca. 1982)
into English by Sersen (1991)

 

[crescentgems]

In Sarandib [Sri Lanka] and its environs, ruby is treated by fire. People take pebbles from the earth and crush and compress them into a mass with the aid of water. [This mixture] is daubed completely around a dry stone. Then, the whole thing is placed on a rock with other rocks set down around it. Dry firewood is thrown on top, lit and blown upon [with bellows]. The blowing is applied, along with more wood, till any black overtones on the ruby have disappeared.

Yep , That`s the old method , It was used for hundreds of years . there were professional blowers, they used to take turns and keep the fire burning for days . mostly used charcoal
there are very few blowers now , these days its all in the Gas and Electric furnace.