Heat treated?????

[handy]

So what does heat treaded do. Doesit affect the value any? just wondering

[Eu_citzen]

Depends on the rock in question.
Sometimes it changes the colour (i.e. darker or lighter), it can affect clarity in certain gems.. All depends on what kind of gem you've got.

As for changing value... That also depends on the gem.
For example I'd rather pay more for a good not treated Sapphire then for a good treated sapphire.
Although Sapphires are routinely heat treated to change colour, remove silk and so on.

However generally speaking, no it does not affect value. In some cases like Tanzanite it actually improves value by giving the Tanzanite its blue colour. "Natural" Tanzanite (not heated, neither by nature nor man) is of a brownish colour.

What kind of rock are you thinking about specifically?
Some gems do not respond to heat treatment at all. Like some tourmaline (green, Elbaite) does not react to heat treatment.
Though some green tourmaline from Africa does actually get a lighter green colour. (Chrome Tourmaline)

[handy]

thank you very much i was just looking around on ebay seen some heat treated some not and wanted more info thank you again

[Eu_citzen]

Your welcome.
If you have any other questions, ask away.

[centfladigger]

I cook my coral all the time, I sell alot of it to the flintknappers but I love to work it when its cooked, I cook alot of brazilian agate also, saves my wheels. If you have a kilbn try it if not and your not familiar using the charcoa method, get an old or a cheap turkey roaster that goes to at least 400-500 and take the pan out and fill it with sand and put your spalls or slabs in there and hold it 200 for a few hours and ramp it up to the max and hold it.

[Eu_citzen]

What is the purpose of cooking agate, coral etc? Just curious.

[stevemc]

It puts in color. Sometimes it is wanted, and sometimes it is not as planned. You have to be used to what heating can do. Saphires are often heat treated, to bring out the colors.

[Eu_citzen]

Good god.. The more you learn about the gem industry the more disappointed you get..

Sapphires are almost always heat treated, to lighten or darken the colour.
Or remove asterism/chatoyancy or even add it if enough Titanium is presently dissolved in the stone.

[claymation]

It puts in color. Sometimes it is wanted, and sometimes it is not as planned. You have to be used to what heating can do. Saphires are often heat treated, to bring out the colors.

AS for the case of flint knapping, would "cooking" also make the pieces easier to work ? I mean, does heat treating also aid in a more predictable flake ? I've often wondered as I've found many flint chard's in and around old campfire rings.

Eu_citizen; I know what you mean, makes me think twice before I buy anything now.

[centfladigger]

yes it does, the paleo indians didnt have heat treating technology it started in the archaic ages. It does change the workability of the rock. Coral is a 7 on the mohs scale of hardness and is a bugger to knap raw, hinges, tears etc. when you cook it it glasses up and your flakes run across and works alot better.