BE treatment = Diffusion treatment?!

[Kashmira]

A true "newbie question": Does BE treatment equal diffusion treatment when it comes to sapphires?

 

[Lady_Disdain]

Yup - berillium is diffuesed into the crystal structure of the sapphire.

 

[morecarats]

Date: 11/26/2009 4:05:50 AM
Author:Kashmira
A true ''newbie question'': Does BE treatment equal diffusion treatment when it comes to sapphires?

It would not be strictly correct to say that BE treatment equals diffusion treatment. Beryllium is just one element that might be diffused into sapphire to change the color or the clarity.

So there are types of diffusion treatment that don''t involve beryllium at all, but rather involve other elements such as titanium, iron or chromium. Many star sapphires are diffusion treated, but not with beryllium.

There are also different kinds of diffusion. Some elements are heavier and cannot penetrate far into the gem. The result is what is known as surface diffusion. Some lighter elements, such as beryllium, can penetrate deeper into the gem (lattice diffusion).

Possibly more than you wanted to know ...

 

[Kashmira]

Thanks for your replies!

I am mainly interested in this type of treatment for padparadscha sapphires and I guess that it is correct to say that they are diffused treated with beryllium. As I understand it the colour of padparadscha sapphires are caused by iron and chrome. Why is beryllium used and not iron or chrome when sapphires are diffused treated in order to get the "pad colour"? Can any sapphire colour be turned into a pad colour using diffusion treatment?

Also are padparadscha sapphires normally surface- or lattice diffused (I guess lattice diffuced as BE could penetrate deeper into the gem)? Also what is "bulk diffusion"?

I am sorry for all questions...

 

[morecarats]

Padparadscha sapphires are not diffusion treated. In fact this is one of the first things a gemological lab will check for in certifying a candidate padparadascha. If diffusion treatment is detected a sapphire would not be certified as a genuine pad. Some labs will accept simple heat treatment.

There are some sapphires which have been beryllium diffused to create an orange-pink color, and some unscrupulous dealers have been known to try to pass them off as padparadscha. Any careful buyer would insist on lab certification before paying a typical padparadscha price.

"Bulk diffusion" is just another term for "lattice diffusion".

 

[Kashmira]

Date: 11/26/2009 7:25:21 AM
Author: morecarats

Padparadscha sapphires are not diffusion treated. In fact this is one of the first things a gemological lab will check for in certifying a candidate padparadascha. If diffusion treatment is detected a sapphire would not be certified as a genuine pad. Some labs will accept simple heat treatment.

There are some sapphires which have been beryllium diffused to create an orange-pink color, and some unscrupulous dealers have been known to try to pass them off as padparadscha. Any careful buyer would insist on lab certification before paying a typical padparadscha price.

''Bulk diffusion'' is just another term for ''lattice diffusion''.

English is not my native language and I understand that I didn''t express myself clearly. I guess I should have written "padparadscha coloured sapphires" and not "padparadscha sapphires"...

I know that diffusion treated padparadscha coloured sapphires are per defintion NOT pads.

What I am wondering is what sapphires (colours) are diffused treated to get the "padparadscha colour"? Why is beryllium used? Why not chrome and iron since the "padparadscha colour" comes from trace amounts of chrome and iron in the aluminiumoxide?

 

[morecarats]

The gem burners in Thailand who invent these treatments experiment with many different chemicals, temperatures and oxidizing and reducing environments. Their methods tend to be closely guarded secrets. If you are looking for information to produce padparadscha-colored sapphires, you will need to contact somoene like Ted Themelis in Bangkok who offers courses on heat treatment of corundum.

I''ve observed the process but I''m not an expert and have no detailed technical knowledge of the process. Beryllium, a constituent element in some gemstones such as beryl and chrysoberyl, tends to turn weak-colored corundum yellow, depending on the original color. Weakly-colored pink sapphire from Madagascar was typically used to produce the padparadscha-like colors. Most of the BE-treated corundum you''ll see in the market is off-color Songea sapphire from Tanzania that has been colored yellow or orange.

If you plan to experiment with berylliyum diffusion, please be aware that beryllium-containing dusts are toxic if inhaled. Beryllium produces a direct corrosive effect to tissue, and can cause a chronic life-threatening allergic disease called berylliosis in susceptible people. Beryllium is classified as a Category 1 carcinogen, so please be careful with this stuff.

 

[Kashmira]

Date: 11/26/2009 8:49:24 AM
Author: morecarats
The gem burners in Thailand who invent these treatments experiment with many different chemicals, temperatures and oxidizing and reducing environments. Their methods tend to be closely guarded secrets. If you are looking for information to produce padparadscha-colored sapphires, you will need to contact somoene like Ted Themelis in Bangkok who offers courses on heat treatment of corundum.

I''ve observed the process but I''m not an expert and have no detailed technical knowledge of the process. Beryllium, a constituent element in some gemstones such as beryl and chrysoberyl, tends to turn weak-colored corundum yellow, depending on the original color. Weakly-colored pink sapphire from Madagascar was typically used to produce the padparadscha-like colors. Most of the BE-treated corundum you''ll see in the market is off-color Songea sapphire from Tanzania that has been colored yellow or orange.

If you plan to experiment with berylliyum diffusion, please be aware that beryllium-containing dusts are toxic if inhaled. Beryllium produces a direct corrosive effect to tissue, and can cause a chronic life-threatening allergic disease called berylliosis in susceptible people. Beryllium is classified as a Category 1 carcinogen, so please be careful with this stuff.

Thanks- now I understand better! I for sure do not intend to experiment with this. I am not in the "gem business" (and I don''t like this kind of treatment methods)- I just wanted to learn more!

 

[Sagebrush]

The subject of diffusion treatment is very complex and there are a number of ways to divide it into types. For the purposes of valuing gemstones, I divide the types into two: Internal and external.

Internal: Even heat treatment is a form of diffusion because concentrations of elements are broken up and spread out, are diffused through the entire stone. Titanium oxide (rutile) in sapphire for example. May improve the color and clarify the crystal as in ruby or improve the color and muddy the crystal as in blue sapphire. All quality parameters being equal, heat treated gems are priced lower than those that are not treated.

External: Here is where the price of a gem is decreased dramatically. There are lots of terms used to describe this type of diffusion but the result is the same. External elements such as beryllium are used as a flux, packed around the stone. Then the stone is heated, in effect softening it and allowing the external material to diffuse into the stone. In another type, shake & bake, the material adheres to the surface and is baked on. This type of diffusion introduces and essentially alien material and stones treated in this manner are dramatically less expensive than stones that are heat treated.