Sapphire – Septembers Birthstone Part 1

How To Buy, (Or Sell), A Blue Sapphire

Part 1

(Selecting Color For Non-Scientific People)

Hi, and welcome to this simple guide, on how to understand blue sapphire. Buying sapphires, especially blue sapphires, can be quite tricky. In this discussion I will emphasize on how to identify some of the subtleties of color that determine desirability in blue sapphires. My goal is to equip you with some of the skills that you will need. In order to be successful in selling though, you will need to understand the basics, and then be able to convert your knowledge into benefits for your clients. In other words you will have to take what you learn today and be able to weave it into the fabric of your story  as you romance the stone.

This is not a science lesson, it’s is a basic field guide to help you understand and to share your knowledge of blue sapphire.

Over the next few blog posts we will look at color, cut, clarity and carat weight. Let’s begin with color.

In addition to the above mentioned characteristics of sapphires, there are two other very important issues that you need to know about. These two issues are, natural vs. synthetic and treatments. Firstly, we will assume that we are looking at a natural gemstone that was mined right out of mother earth and we are going to also assume that the gemstone is either not treated at all or has been only heat treated. More about treatments another time.

Blue Sapphire – Color

When you judge color, you are actually looking at three things.

You are analyzing hue, tone and saturation.

  • Hue is the basic color. Is it red, yellow, blue or green? See the image below left. I have illustrated by putting food coloring of various colors into test tubes.
  • Tone is how much grey or black is present in the color. Tone can be somewhat misleading to the untrained eye, because a gem with a dark tone may be confused with a gem of intense color. See the image below center. In this example both tubes have the exact same saturation, however the one on the right has had black color added to darken the tone.
  • Saturation is how much of the color is present. Gems with a high saturation of color are often brighter and more valuable. See the image below right. Each green test tube has the same color, however the one on the right has the highest saturation of green.

Hue – Is The Basic Color Red, Yellow, Blue, Green

Tone – How Much Grey Or Black Is Present

Saturation – How Much Of The Color Is Present




Now let’s apply this to blue sapphire. Sapphire is simply the crystalline form of aluminum and oxygen (Aluminum Oxide). It’s also known as corundum. Simple aluminum oxide or corundum, is colorless. So in its purest form, sapphire is colorless. See the image of the near colorless sapphire on the left. For more information click here.


SKU#15333, white sapphire

  • Now to get a blue sapphire, the aluminum oxide needs to have a sprinkling of the trace elements, iron and titanium.
    Then, if you add a dash of chromium to the recipe, you get the violet or purple undertones. So that means that a blue sapphire can have several secondary shades of color.
  • When light goes through a sapphire it splits into two rays called double refraction. These two split rays, travel through the gem at different speeds, giving two slightly different colors. How is that done? Well, like I said this is not a science lesson. Simply put, all blue sapphires display two colors. Most commonly you will see either a blue with green as a secondary color or blue with violet as a secondary color. The most valuable colors are blue with very slight violet. Blue with the slight green is often not as bright and this color combination generally brings the price down by roughly 30-40%.

The Most Prized Hue of Sapphire Is Blue With A Slight Secondary Violet Color


Left – SKU#12941 violet- blue sapphire,  Sri Lanka. For more information click here

Blue sapphires with violet as a secondary color are commonly associated with gems from Sri Lanka, Burma and Southern Madagascar. If you are a gem geek that means they come mostly from metamorphic rocks and have a lower iron content. These gems are the ones that are more vivid in color and command a premium price.


Left – SKU#13872 greenish blue sapphire, Nigeria. For more information click here

Blue Sapphires with a slight green as a secondary color are commonly associated with gems from Thailand, Cambodia, Northern Madagascar, Nigeria and parts of the USA. These gems are more commonly more directly associated with volcanic activity and contain a lot more iron. Generally, they are much less pricey. Now don’t let that deter you from buying the greenish blue color. Based on fashion and your personal taste, this teal color may just be exactly what you are looking for.

Blue Sapphire (Tone)

  • The second part of looking at color is evaluating the tone. Tone is the amount of gray or black that is present in the stone.

See the gradient to the left? I photoshopped this picture of a sapphire to illustrate. The top picture shows the same hue with a very light tone. The middle picture shows a medium tone, which is in essence the most desirable tone and the bottom picture shows a dark tone.

The best way to tell if a Sapphire has a dark tone is to look at it under a variety of light sources. Place the gem on the back of your hand and go outside into the sunlight. If it looks even brighter under an intense light source, then it may have an ideal, medium tone. If the color kind of washes out or looks grayish then that may be an indicator of a darker tone, which generally is not as desirable. If there is no sunlight, try looking at the gem under different light sources such as an intense flashlight. You will be amazed at what you will see.

Blue Sapphire (Saturation)

Finally, there is saturation, which is the amount of color present. Here’s a simple illustration below.

  • Each of the three gemstones is from Sri Lanka and display the same basic hue. The gem on the left has a very low saturation, the one in the middle a medium saturation and the one on the right displays a high level of color saturation, commonly known as ‘royal blue’.

Low Saturation Click Here

Med. Saturation Click Here

High Saturation Click Here


While the most highly saturated blues command the highest price, many shoppers actually prefer the sparkle of a medium or lighter saturated gem.


Many people have asked me, what is the most perfect mix of hue tone and saturation for a blue sapphire? While that question is really up to the buyer and what they find most attractive, the sapphires that commend the highest prices are a highly saturated, slightly violet blue color, with a medium tone.

See image below. Fine quality, 3.03ct, highly saturated, medium tone, sapphire. Click Here for more about this gem.

So, happy gem hunting and as always feel free to reach out to us at Artinian Gems with your comments and questions and we will do our best to help you in any way we can.