Blue Sapphire Buying & Treatment Guide – How to buy and tell the difference between natural unheated, heated, lattice diffusion treatment, and the brand new glass-filled sapphire?

Video explanation between unheated sapphire vs heated sapphire (rutile silk):

Why is it Important to Learn About Sapphire Treatments?

Distinguishing between natural, no treatment sapphire with heated or new treatment sapphires is a very important skill every gemstone buyer should learn before venturing out to buy one.

The price between each level of treatment can range from.  The exceptionally expensive US$5,000 per carat for unheated natural sapphires.  To US$1 per carat for the new treatment lattice-diffused sapphires which has now flooded the market today.  This is especially true with many dealers on eBay especially in Thailand.

Understanding what to look for and checking the authenticity of the certificate.  Can make a difference between buying a sapphire which you got a great deal.   And buying one that you got scammed as the seller did not inform you what type of treatment the stone has had.

I hope this guide will provide you a basic understanding in how to distinguish the different types of treatments.

I do want to emphasize that even though you have read this guide and completely understood the basics. It does take years of experience of seeing sapphires to truly understand and distinguish the different treatments.

If there is any doubt about your purchase. “Even that slight 1% chance.” It is always best to double-check 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 quite easy to distinguish.  If they have natural inclusions inside which you can see through a microscope and normal 10 times (10x) magnification loupe.

Natural Inclusions Include the Following:

  • 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 experience. To check and verify if the sapphire you are looking at is completely natural or not.

However, if you do see these inclusions.  And NONE of the other inclusions described from the guide below. You can be sure that the sapphire you have in hand is natural, unheated and untreated, the rarest of all sapphires!

Blue Sapphire Treatment Guide - Unheated Blue Sapphire - Intact Negative Crystal
Intact Negative Crystal in Madagascar Blue Sapphire. Photo courtesy from © GGTL Laboratories
Blue Sapphire Treatment Guide - Unheated Blue Sapphire -Intact Rutile Silk Inclusions
Intact Rutile Silk Inclusions which proves this is natural blue sapphire.  Photo courtesy from © GIA

Sapphire Treatment Guide – Heated

Almost all sapphires (95% of them) today are heat-treated. There are different types and level of heat treatment in sapphires that can be classified from very slight to quite extreme.

Distinguishing these levels of treatment can also affect the price of a sapphire dramatically.  Heat treatment is used to either develop or intensify a sapphire’s natural color.

Heat treatment can also improve the clarity of sapphire. It 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 love to heat sapphires.

Ways of Detecting “Normal Heat” Treatment Sapphires are by Seeing the Following Inclusions:

  • Discoid fractures with tension halos. Looks like disk-like fractures with lace-like outer healing rims. This are 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 which you are purchasing has not been subject to newer or higher step treatments.  Which is shown next topic below.  Because the price for higher treatment sapphires can drop dramatically.

A good way to double-check if the sapphire is what is stated. Is by asking your jeweler or gemstone wholesaler for a reliable certificate with the stone.

On a GRS certificate (GemResearch Swisslab).  One of the reliable color gemstones certificate laboratories in the market.  It will state the sapphire is only subject to H treatment or H (a) is also acceptable.

If it is written H (Be) or the newer hybrid sapphire treatments. Then you will know that the sapphire has been subject to newer treatments. And so you should not pay the price for normal heat sapphire.

For all the GRS classification details. You can click on the following link:

Blue Sapphire Treatment Guide - Heated Blue Sapphire - This image shows discoid fracture with tension halos and burned, altered mineral inclusions (in the middle) with rounded
This image shows discoid fracture with tension halos and burned. Altered mineral inclusions (in the middle) with rounded “cotton” like or “snowball” look. This proves this blue sapphire is heated. Photo courtesy from © GGTL Laboratories
Heated Blue Sapphire Image - Partially healed fissure containing melted residues which proves this blue sapphire has been heated.
Partially healed fissure that contains melted residues.  Again, this blue sapphire has been heated. Photo courtesy from © GGTL Laboratories

Sapphire Treatment Guide – Lattice Diffusion Treated Corundum

Extreme heat treatment which induces foreign materials in sapphires is the next higher step of treating sapphires.  This is called Lattice diffusion.  On reliable certificate providers, they will indicate these new treatment sapphires as H(Be).

Treaters add this “foreign” material into the sapphires by heating it in extreme temperatures.  They then diffuse substances like beryllium (light element) or titanium (heavy elements) into it.

These elements help enhances the blue sapphire color.  And therefore make the stone look more vivid or blue compared to the original state. As these elements were introduced by man this makes diffused-treated sapphires less rare and worth substantially less.

Signs to Check for Diffused-Treated Sapphires are Explained Below:


  • Color concentrations along facet junctions and girdle edge
  • Localized or blotchy color that “bleeds” inot pits and surface-reaching fractures
  • The above features are best-seen trough 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 sparkle of the gemstone


  • 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.

Images in how to detect both types of diffusions are provided below. The price for these types of sapphires is substantially cheaper from US$1 to US$20 per carat.  This is because new elements have been introduced by man.  Which makes these stones “less rare and not so good looking sapphires” more marketable.

Diffusion Blue Sapphire detection - This blue sapphire shows shallow depth of foreign element treatment as you can see from color concentrations along facet junctions and girdle edge. This proves this blue sapphire has been treated with lattice diffusion with heavy elements.
This blue synthetic sapphire shows a “shallow” depth of foreign element treatment. As you can see from color concentrations along facet junctions and girdle edge. This proves sapphire has been treated with lattice diffusion with heavy elements. Photo courtesy from © Robert E. Kane et al., “The Identification of Blue Diffusion-Treated Sapphires,” Summer 1990 Gems & Gemology; photos by Shane F. McClure.
Blue Sapphire Treatment - Beryllium Diffused Sapphire - This pictures show the colorless zone around the outside of an otherwise blue stone, which proves lattice diffusion with beryllium. Photo courtesy from © Richard W. Hughes
This pictures show the colorless zone around the outside. Of an otherwise blue stone, which proves lattice diffusion with beryllium. Photo courtesy from © Richard W. Hughes

Sapphire Treatment Guide – Lead-Glass Sapphires (New Treatment or Phua Mai in Thai)

The newest type of sapphires which I just heard of a few months back is lead-glass filled sapphires. I was a surprise because I thought it existed only in the case of rubies.

If you do find a sapphire which is written as “composite sapphire.” Then you will know this is lead-glass filled and the average price is US$ 1 per carat or less.

These stones are not worth anything.  This is because in their natural state the rough would have been an ugly, highly included gray color.  That would NOT have been saleable if it was not subject to this type of treatment.

As this is a new type of treatment I am still not sure how they have treated these stones. But I will assume it will be very similar to its corundum cousin (ruby). Please be careful with these type of stones.  You might think this is a beautiful natural sapphire, which I am getting in a cheap price.

The problem with this type of treatment is many as listed below:


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 sellers actually disclose the treatments of these stones to their clients.  The purchaser can then make an informed decision in how much one should pay for this type of sapphire.


Due to not being purely corundum anymore. This type of sapphire if you set in jewelry without informing the setter will get ruined in a second. If the jeweler torches the ring for resizing and it touches the stone for a second 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, the wearer is not careful in wearing these “hybrid” sapphires. For example, accidentally spill some lemon juice while eating fish. The stone will slowly decay in few days.  And your supposedly “beautiful” stone.  Will now look like it was thrown from 50 storey high rise building.

Therefore, if you are in the market to buy sapphires it is very important to find out.  How to check for these types of sapphires.

Sure Indications are Listed Below:

  • Gas-bubbles are sure indications of glass-filled sapphires or synthetics.  Usually very easy to spot under microscope or a loupe with dark light background.
  • Blue and Orange flash effect along structural fractures when put under a black light. Is also a key indication of lead-glass filled sapphires

Again, the best way to find out if the stone you are buying is lead-glass filled sapphire.  Is either by having a great pair of eyes and check for the signs above or by getting the stone certified by a reliable lab.

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 has Composite Sapphire”

Glass-filled blue sapphire lot that came across our office last month. Looks like normal sapphires with naked eye, but when you see it under gem loupe or microscope you can tell its not a
Glass-filled blue sapphire lot that came across our office last month. Looks like normal sapphires with naked eye. But when you see it under gem loupe or microscope you can tell its not a “natural” blue sapphire. Photo courtesy from © Thai Native Gems

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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16 thoughts on “Blue Sapphire Buying & Treatment Guide – How to buy and tell the difference between natural unheated, heated, lattice diffusion treatment, and the brand new glass-filled sapphire?”

  1. Ramal sampath perera

    Thank you very much give to this information very usefull is buying gemstones, and peoples are in gem business field or not, are borth them have get from knowlege &experiance about this article.i am very appriciated with you this article. thankyou.

      1. This type of stones are in the market . Used in most silver jewellery. It doesnt matter as long as sold cheep and tell the customer its way of treated. Because of the good natural treated gudas saphires are expensive in price .

        1. Thanks Riza for your comments. Agree with you that all jewelers and manufacturers should disclose the treatments and if they don’t I hope these buying guides help. This is the reason why I created this blog as I believe being more transparent will help the gemstone trade overall.

  2. teleoneconsumers1

    thank you for sharing a details about gemstone. Blue sapphire is best gemstone. I love gemstone.

  3. hi i think this blog is having very good message about gemstones. you know what birth stones depend on according to their birth date. A colourful assortment of dazzling gemstones generally bears month wise association. Both traditional as well as modern category involves similar correlations.

  4. My husband just recently bought me a blue sapphire glass for a wedding anniversary. I am just curious to know what is the best way to take care of it so that it will stay around for awhile. It’s good to know that regular treatments help concentrate the colors.

    1. I have purchased natural blue sapphire but in sample laboratory test its found natural blue sapphire natural corundum nice colour nice cut.. but in test report its written mentioned micro factures***** 8 carat + price is Rs.15000 per carat..
      Is this will work positively,should i wear it or not to wear micro factures inclusion natural blue sapphire..
      please reply.

      1. Hi Vikram,
        Just curious the name of the lab which certified your stone. This is very important to determine if the certification is reliable. I am especially cautious regarding gemstones from Indian dealers as they are very well renown in selling “dyed sillimanite” which can be dyed green, red or blue and than inform their customer that stone is a ‘natural ruby, sapphire or emerald.” You can search more about this with a simple google search.
        Otherwise astrology-wise, if the gemstone is ‘natural blue sapphire’ and is highly included they do say it will have a ‘smaller or less’ effect compare to clean blue sapphire. Also, ideally the prefect astrological gemstone should be 100% natural with ‘no treatment’ and with no black spots or inclusions. You can read more about this in our previous blog post:
        However, please note getting a ‘clean’ nice color, 8 carat unheated & untreated blue sapphire is rare and very expensive, so you should also check what your budget is. In the end, I do believe your luck is determine by your karma & efforts and one should not ‘bankrupt’ themselves in getting a ‘nice gemstone’ just to make their luck change. Anyways, do wish you the best of luck.
        Tarun Gupta, Graduate Gemologist (GIA)

  5. this is very important article to any one who interest in buying or do business in gem feild especially in saphires. i have a question too that i bought a bracelet in 9 kt gold with 9 peices of B/S of nearly 5 carat heated and with 8 peices 1 point Diamond. so could you tell me how much it could be the cost ?? thank you

    1. Hi Sharifdeen,
      It is very difficult to determine the price without looking at actual bracelet, and seeing what quality the blue sapphires are (and the diamonds used)? The information you have provided us is just average carat weight which is around 1.8 carats (=9 pieces/ 5 carat) and assumption the stones has been subject to heat treatment. As seen in this article there many different levels of heat treatment so we have check ‘what exactly the treatment was.’ Finally, other factors we have to check before we can determine your bracelet price is what the diamond & blue sapphires color range, clarity range, and where the blue sapphire’s origin is from.
      Best Regards,
      Tarun Gupta, Graduate Gemologist
      Managing Director Thai Native Gems (1960) Co., Ltd.

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