Video explanation between unheated sapphire vs heated sapphire (rutile silk):
WHY KNOWING ABOUT SAPPHIRE TREATMENTS IS IMPORTANT?
Before buying any sapphire it is important to know what type of treatment it has gone through.
Sapphires have different levels of treatment.
- Natural (no treatment)
- Heat Treatment to enhance color
- Lattice Diffusion to enhance color aggressively
- Lead-Glass filled Treatment to change characteristics of a sapphire
The more treatment the sapphire goes through the cheaper it gets!
The price for blue sapphires can range from US$5,000+ per carat for unheated sapphires to US$3 per carat for lattice-diffused sapphires.
Lattice-diffused-sapphires have flooded the gem market from traditional retail stores, online websites to sellers on eBay.
Simply checking the authenticity of the certificate and understanding the ‘treatment’ section, you can save thousands of dollars. This will also save you time and the harassment of getting scammed by the seller due to them not disclosing these facts to you.
I hope this guide will provide you with a basic understanding of the different types of sapphire treatments.
I do want to emphasize that even by reading this guide, it does take years of experience looking at sapphires to understand the different levels of treatments.
If there is any doubt about your purchase – “Even that slight 1% chance” – it is always best to recheck the stone from a reliable gemstone laboratory or trustworthy gem dealer.
SAPPHIRE TREATMENT GUIDE – UNHEATED, UNTREATED, COMPLETELY NATURAL SAPPHIRE
Natural Sapphire that is NOT heated or treated is easy to check. You only need to see the sapphire through a microscope or gem loupe for natural intact inclusions.
Natural Inclusions Are:
- Intact, fine, needle-like Silk (rutile needles) intersecting at 60 degrees angle. In the same plane or other fine needles at near right angles.
- Fingerprint inclusions.
- Angular, straight, or hexagonal growth zoning or banding.
- Straight, angular, and possible color zoning and color banding.
- Unaltered mineral inclusions, clear or opaque color, that might show angular faces.
- Intact two-phase inclusions.
Below are some sample images of sapphires with these characteristics. Please note that it does take some practice to check if the sapphire is natural or not.
However, if you do see these inclusions and NONE of the other inclusions shown below. You know the sapphire you have is natural, unheated, and untreated, the rarest of all sapphires!
SAPPHIRE TREATMENT GUIDE – HEATED
Almost all sapphires (95% of them) today are heat-treated. There are different levels of heat treatment in sapphires that can be classified from very slight to quite extreme. The more aggressive the treatment the more the price drops.
Heat treatment is used to either develop or intensify a sapphire’s natural color.
Heat treatment can also improve the clarity of sapphire. This is done by removing or reducing inclusions and making them less visible.
The way this works is quite technical and I will not be explaining it in this guide. But you get an idea of why people heat-treat their sapphires. To make them easier to sell.
Inclusions of “Normal Heat” Treatment Are:
- Discoid fractures with tension halos. Looks like disk-like fractures with lace-like outer healing rims. This is caused by the expansion of natural crystal inclusions.
- Burned or altered mineral inclusions. With rounded, often whitish, “cotton” like or snowball” appearances.
- Broken silk or partially “reabsorbed” rutile needles.
- Ruptured two-phase inclusions and negative crystals.
- Sintered surface areas, especially around the girdle.
Prices for normal or slightly heated sapphires are still not cheap. Good ones can still cost upwards of US$3,000 per carat.
However, before paying these high prices, PLEASE make sure the sapphire you are purchasing has not gone through the higher treatments shown below.
The fastest way to verify if your sapphire has not been subject to higher treatments is by asking your jeweler or gemstone dealer for a reliable third-party certificate.
On a GRS certificate, it will state the sapphire is only subject to “H” treatment, or “H (a)” is also acceptable. GIA will classify this level of treatment as ‘Heated.’
If GRS writes H (Be) or the newer glass-filled sapphire treatment. Or if GIA writes titanium diffusion, lattice diffusion of beryllium, or led-glass treatment. Then you know that the sapphire has been subject to higher treatments, which means it will command a much lower price.
For all the GRS classification details. You can click on the following link: http://gemresearch.ch/enhancement-disclosure/
SAPPHIRE TREATMENT GUIDE – LATTICE DIFFUSION TREATED CORUNDUM
Extreme heat treatment which induces foreign materials in sapphires is the next level of treatment for blue sapphires. This is called lattice diffusion. On reliable certificate providers, they will indicate these new treatment sapphires as H(Be), titanium diffusion, and lattice diffusion of beryllium.
Treaters add this “foreign” material into the sapphires by heating them at extreme temperatures. They then diffuse substances like beryllium (light element) or titanium (heavy elements) into it.
These elements help enhances the blue sapphire color. Which makes the stone look more vivid or blue compared to its original state. As these elements are introduced by man, this makes diffused-treated sapphires less rare and worth substantially less.
Indications for Diffused-Treated Sapphires Are:
LATTICE DIFFUSION WITH HEAVY ELEMENTS:
- Color concentrations along facet junctions and girdle edge
- Localized or blotchy color that “bleeds” into pits and surface-reaching fractures
- The above features are best seen through the gem’s pavilion. Gem faced upside down or bottom face towards you. Then immersed in water and diffused light under it. This allows you to see the fact junctions without the distraction of the sparkle of the gemstone
LATTICE DIFFUSION WITH BERYLLIUM
- This light element is diffused in the sapphire. To remove or lighten the blue color in too dark sapphires.
- While doing the treatment, there might be some traces of yellow color in the stone’s interior. This “yellow color” can be removed with subsequent heat treatment. That will make the sapphire “retain” its blue color and thus make it more marketable.
- Magnification and water immersion. As indicated lattice diffusion with heavy elements. Might reveal a colorless zone around the outside of an otherwise blue stone.
Examples of how diffusion sapphires are checked are provided below. The price for these sapphires is substantially cheaper. Ranging from US$1 to US$20 per carat. This is because new elements have been introduced by man. This makes these undesirable common gray or brown sapphires more attractive and marketable to sell.
SAPPHIRE TREATMENT GUIDE – LEAD-GLASS SAPPHIRES (CALLED “PHUA MAI” IN THAI)
The most aggressive treatment a natural sapphire can go through is called lead-glass-filled sapphires.
If you do find a sapphire that is written on the certificate as “composite sapphire,” then you will know this is a lead-glass filled and the average price is US$ 3 per carat or less.
These stones are not worth anything. This is because, in their natural rough state, they would have been an ugly, highly included gray color.
These stones are treated the same way the corundum cousin “ruby” is treated. Please be careful with these types of stones. You might think this is a beautiful natural sapphire, that I am getting a cheap price for.
The problem with this type of treatment is many as listed below.
NOT NATURAL SAPPHIRE ANYMORE
These stones are not sapphires anymore. It is a mixture of natural corundum and lead glass. Actually, most of these sapphires have more lead glass in them. Yet they are still being sold as natural sapphires, which makes this a major disclosure issue.
If the seller actually discloses the treatment, the purchaser can then make an informed decision on how much they should pay for it.
VERY FRAGILE, CAREFUL WHILE SETTING
Composite sapphires can get ruined immediately, if not disclosed to the jewelry setter. If the manufacturer torches the ring for resizing and the heat touches the stone, it will crack.
Also, if you re-plate your rhodium plate white gold ring it will destroy the stone. For natural sapphires, you don’t have to worry about any of the above issues.
Also, if you are not careful in wearing these sapphires they will change over time.
For example, if you accidentally spill some lemon juice while eating, the stone will slowly decay in a few days. Your “beautiful” stone, will now look like it was thrown from a high-rise building after this mishap.
So, if you are in the market buying blue sapphires, it is important to check for this type of treatment.
Inclusions for Lead-Glassed Sapphires Are:
- Gas bubbles are sure indications of glass-filled sapphires or synthetics. Usually easy to spot under the microscope or gem loupe with dark light background.
- Blue and Orange flash effect along with structural fractures when put under a black light. Is also a key indicator of lead-glass filled sapphires
The best way to check if you have a lead-glass-filled sapphire is by having a great pair of eyes or by getting it certified by a reliable lab.
GIA AND GRS CLASSIFICATION
GRS certificates will classify these sapphires as “Hybrid”- Corundum and will have the following comment. “Heat-treated and filled with a foreign solid substance (including lead). Special care when handling. Also known as Composite Sapphire” GIA will also classify these stones as composite sapphires.
I hope the above guide is helpful. If you have any additional questions please feel free to provide your comments below. Or send me a message at [email protected].
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