Heated vs Unheated Sapphire: A Guide

If it is too good to be true, it is too good to be true

Over the years we observed this: shoppers really want to believe there is a cheap and unheated stone that is waiting to be sold. 

These same minds will always ask if something is ‘unheated’, when it really is, considering all factors, too good to be unheated!

Most sapphires are heat treated, let’s say, 99%. 

Thermal or heat treatment is common in commercially sold sapphires, as heat brings out the vivid colors and/or improves the clarity of sapphires.


Be Clear About Terms

    1. Sapphires that are heat treated are still considered natural, insofar that they are earth-mined and have not been chemically treated.

    2. Heat treatment in sapphires is a traditional treatment practised for centuries in Sri Lanka and now worldwide. Heat treatment is acceptable and should be assumed.

    3. Heat treatment is not chemical treatment. Do not confuse heat treatment with chemical treatments like beryllium or diffusion.

    4. Chemical treatment includes beryllium treated sapphires, also called ‘new heat’. Beryllium treatment is a chemical treatment that is stable and produces fiery sapphires in myriads of colors. Another common chemical treatment is flux; flux treatment is not the same thing as beryllium or diffusion.

    5. Unless stated and certified to be ‘unheated’ or ‘no heat’, the general rule when shopping for sapphires is to assume the sapphires you see on a ring or a pair of earrings are heated.

    6. Any chemical treatment is unacceptable unless clearly disclosed. 

    7. Heated or unheated, the demand for sapphires with vivid colors does not abate, especially when compared to less vivid colors in otherwise natural sleepy sapphires. What consistent demand does is actually to drive up the prices of even heated sapphires to a high. It is not unusual a vivid heated sapphire is priced more or as much as an unheated sapphire that is lacklustre in color.

    8. In short, TWO pervasive factors determine the price of a natural sapphire: whether the sapphire is heated or unheated, and how vivid its color (sometimes called how ‘fiery’.

Ask not "What is the price of sapphires per carat" but "What is available for sale"

Due to the ‘scarcity’ of unheated sapphires, it should be no surprise that market forces of demand and supply dominate when it comes to the price of sapphires.

Good quality unheated sapphires will cost you. Unheated sapphires below 3ct are affordable, but the price jump is exponential for sapphires above 5ct.

This is because it is easier to cut high quality unheated sapphires under 3ct, than getting the same premium quality over a bigger stone. Hence the price jump is justified by how hard it is to source and then cut a fine quality material over a high carat. Small is easy; big is lucky.

The best way to determine real prices is to work backwards: see what is available for sale, then make some connection to the price range (per carat) of sapphires over fair, good, and premium grades.

Price & Origin

Unheated sapphires, depending on color (vivid/fiery), and broadly speaking:

  1. < 3ct will range between USD800 to USD1,800 per carat.
  2. > 5ct will range wildly from USD2,000 to USD4,000 per carat.
  3. > 10ct with every 5ct jump in size raising prices.

Carat weight aside, the origin of a sapphire will significantly affect asking price. This is evidently so for sapphires > 10ct.

Again, broadly speaking:

Kashmir – Burma – Sri Lanka

This preference ladder depicts the collector frenzy when it comes to the pursuit of sapphires.

Note that Kashmir sapphires of quality are always the same stones sold and resold numerous times, and current production of good material from Mogok is very limited. Kashmir sapphires are usually unheated, while Burma sapphires could be heated or unheated. Recent Burmese stones are more often heated than not.

Sri Lankan (Ceylon) sapphires are prized much higher than Montana or Australian sapphires, mostly because the color of Sri Lankan sapphires tends to be more saturated. Many Sri Lankan sapphires also tend to undergo only low heat treatment (this varies, since heated sapphires with vivid colors are always in demand, even if not low heat).

Sri Lanka produces a wider range of sapphires than any other classic source. It is also known for ‘fancy’ sapphires, colors other than blue, including the coveted orange-pink Padparadscha sapphire. Traditionally, padparadscha sapphires hail from Sri Lanka, though newer deposits from Madagascar have come to the market for awhile now.

Hence, it is truer to say that outside obsessive collector activity, demand always exceeds supply for all quality sapphires, heated or unheated, certainly when color falls into any of the below.

Lotus Gemology’s Ruby & Sapphire Color Types guide is a good benchmark, also further reading.

Lotus Guide


Color is king.

As jewellers of course we’d say this. Color is the waterfall that makes the jewel.

Below are some visual maps of our take on blue.

Disclaimer: the color charts are our sentiments from the observation of color in sapphires we routinely come across and sell, not from a gemological ‘science’ of colors.

Can you guess which hue(s) we probably will only encounter ‘once in a lifetime’?

Blue Sapphire Color Chart
Blue Sapphire Color Chart 2
Blue Sapphire Color Chart 2bb
15.74ct pair royal blue sapphires2
Not many are aware, but Royal Blue sapphires have a violet undertone. A Royal Blue sapphire can be very dark, if not for this violet undertone that 'lightens' its saturation.
3.6 3.63 vivid blue sapphires pair
Vivid Blue. It is sometimes highly subjective whether a hue is Royal Blue or Vivid Blue. Note that both terms are used descriptively by dealers (when selling) and even gemologists can be subjective (yes, even in actual gem reports).

How we see color is subjective, no?

This includes gemologist to gemologist at gem labs, jewellers, dealers and collectors. One thing is for certain, the more you handle and study stones, the less subjective your determination of color.

Because color can be a matter of much debate, GIA uses industry naming conventions like ‘Royal Blue’ or ‘Pigeon Blood’ to word their findings only very rarely. ‘Pigeon Blood’ has to be transparent and clean, where the attribute of red is not the single determinant.

GRS is comparatively ‘liberal’, and much more descriptive in their color identification, and you will encounter ‘Sunset Padparadscha’, ‘Sunrise Padparadscha’, etc. When it comes to padparadschas, because there is so much difference in tone and hue in this coveted gem, such descriptions of color can be helpful. 

When shopping for a sapphire, it is unrealistic to believe anything other than your eyes. While a reputable gem report can tell you what you are buying (or what you are investing in), it cannot tell you what color to love. 

It is more realistic to expect what you don’t get in your first gem you may at your second, or third. Collectors of stones know this intimately.

The light of travelling by gems is a journey sparked from gem to gem. One stone will tell you more – some correction to the past, some confirmation of the present and then some questions of the future – not unlike love affair to affair.

The Practice of Color

This is the fun part. The more you see, the more you feel for. 

In fact, the more sapphires you encounter, the more likely you will come to appreciate color as an indication to how ‘natural’ a stone is.

Many unheated sapphires are not that flat, one color, eye clean stone you see in the color charts of sapphires. And it is this naturally silky (not sleepy) state of the sapphire at one glance that informs the jeweler or dealer eye it is an unheated, natural sapphire, even without the need for a loupe, and sometimes in a cluster of sapphires!

Blue Sapphire Color Chart 2a
Sapphires that are Dark Blue or Deep Blue in saturation. What does Dark Blue actually mean?
3 deep blue sapphires
Think of Twilight (left, both) as deep blue and sometimes with a tinge of green, closer to Blue Black. Think of Indigo as deep blue, nothing more.
Three unheated blue sapphires perched on top a 78ct rubellite.
L to R: PEACOCK Blue, VIVID Blue, VELVET Blue - individually their blue distinctions are easy to understand, but placed beside one another they are just but shades of blue that will take a trained eye and even so...
intense blue red
Intense Blue & Intense Red. Sometimes, it helps us to see one color very specifically when we 'pit' a corresponding color sharing its intensity.
indigo blue twilight
Indgo Blue & Twilight. These sapphires are sometimes described as 'muddy' due to their bi color. Very often, the existence of more than one color in the sapphire makes the stone 'distinct'. It is hard to find one when you are actually searching for one. Many bi color sapphires are unheated, since heat treatment removes the secondary color.

Should I pay for an unheated sapphire?

This is the no-so-fun part, the money. The conundrum is, the more you know, the more you think (or not) you want the same thing as everyone.

There are all kinds of reasons to do so and all kinds to not. It is more useful to consider why jewelry artists and designers choose to use unheated sapphires.

One reason has to do with the perception of beauty and its impact on value. Designers and high jewelry want to showcase their craft and style, and sometimes to do so, it is only worthwhile to put their creative efforts to sapphires that are 101% natural (100% natural plus the superlative 1% of worldwide supply). That is, their colors must be exactly the way they are when they are mined from the earth and nothing else is acceptable.

Consider also that sapphires sought out for occasions such as engagement or anniversary have more emotive reasons to demand for that 1%.

If you have time and interest, read our Unorthodox Guide: How To Buy Sapphires. In this article, we list some scenarios when it is a good idea to buy heated sapphires. Sometimes knowing when The Other Option is a good idea will help make an informed decision.

Gemological Labs vs Jewelers & Dealers

The grading of stones generally fall into two sources: gemological labs and jewelers.

Gem labs will provide you with the basic info about identification, country of origin, and the presence or lack of treatment. Problem is, most of the top international gemological labs that document sapphires and other gems do not actually grade stones or appraise value.

There exists too much potential for conflicts of interest, as you may imagine. Which explains why smaller gem labs have sometimes come in to fulfil this gap, grading and appraising in addition to identification. Here then lies possible areas for contention, which is why some stones can have two (or three) differing certification papers.

It is now common for many jewelers who are also independent gemologists. Again, realistically speaking, the same potential for conflicts of interest prevail.

Our final word is this. When purchasing fine or luxury gems, it makes sense, both financially and intuitively, to consult with more than one experienced jeweler-dealer to provide you with market-realistic grading and price indicators. 

Know where your cert is coming from. But get an independent grading and price information. This I find is always possible from a straightforward jeweler, who knows intimately the forces of demand and supply. This sapphire cost X. What will happen if I sell it in a few years? 

In some countries, like Singapore, no gem lab is seriously doing the grading and price information appraisal on paper, as they understand it is unreliable when it comes to the actual paying for and selling for (ie. who is buying, who is selling). This means you will be getting your grade and price information only verbally.

Our World Is A Magical Smoke Screen: Heated or Unheated?

We cannot speak for other jewelers but for ourselves.

I refrain from using the term ‘ethical’ as this has become embroiled with commercial motives and the outcome is laughable – our stand then as a mindful artist-jeweler is to assess the reason for pursuing an unheated sapphire.

Our approach is simple, and sentimental. If it is the one piece of jewelry you are likely to want or purchase (and affordability is not an issue), an unheated sapphire is a good idea. But not if the search becomes tedious and seemingly endless… we know a handful who look for the perfect sapphire for years, fruitlessly!

If you already have a few jewels or will expect to have more in future, or if you are more of a jewelry lover than a stones lover, it is more satisfying to get sapphires that have the color you want, heated or unheated.

In David Lynch’s world, the past dictates the future. Being open is being curious. Whatever your preference today should hardly answer future questions.

3 thoughts on “Heated vs Unheated Sapphire: A Guide”

  1. I learned a lot from the article. I knew nothing to start with and now know the rudiments of raw gemstone. I find the stones in an auction in their raw state interesting and will probably purchase a cheap one just to see and feel it


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