Do you really know sapphire?
Traditionally sapphire is invariably associated with blue.
The sapphire is part of the very closed club of precious stones which counts only four members: the diamond, the ruby, the emerald and thus, the sapphire. But did you know that there are other colors of natural sapphires? Green, pink, yellow, orange, black, white or even colorless, sapphire surprises us with its wide range of colors. So, do you really know sapphire? We propose to lift the veil a little on this fascinating stone.
The origin of sapphire
This so-called blue “gemstone” has many shades of blue depending on various criteria.
Chemically speaking, it is an aluminum oxide colored by titanium (which gives it its blue color) and by iron (which darkens the gem more or less depending on the iron content).
The name sapphire comes from the Latin sapphirus and the Greek sappheiros “blue stone” which comes from the Hebrew sappîr meaning “the most beautiful thing”. Sapphire was known in ancient Greece as hyacinth, the name given to the blue iris.
This stone is so well known for its blue color that when we speak of “sapphire”, it is associated with this hue, otherwise we must always specify the color of the sapphire (because yes, sapphire has many colors).
By the way, sapphire and ruby are the same stone, but the former is blue while the latter is red, they both belong to the corundum family.
It is the most scratch-resistant gem family after diamond with a hardness of 9 on the Mohs scale.
The colors of sapphire
The blue color is the best known hue of sapphire. When sapphire is blue, it means that it contains chemical impurities of iron oxide and titanium. Shades of blue vary with each gem, ranging from violet blue to green blue.
Yellow (or orange) sapphire
It is the iron that gives sapphire its yellow (or orange) hue. The purity of yellow sapphire makes it an alternative to the much more expensive yellow diamond.
Pink sapphire is actually a lightly tinted ruby. Like ruby, it is a corundum that contains chromium. When the amount of chromium is less, the ruby becomes a pink sapphire. Pink sapphire often replaces pink diamonds because it is much more affordable.
White sapphire is quite rare. It is a corundum free of impurities. It has long been used to replace diamonds before the appearance of synthetic diamonds.
This is the least known of the sapphires. Like yellow sapphire, it owes its hue to the presence of iron oxide. More resistant and less expensive, it is sometimes chosen instead of emerald.
The price of sapphire
The price of sapphire varies from a few dozen euros for a carat to tens of thousands of euros for the most valuable stones. In traditional jewelry, sapphire prices generally range from €200 to €3,000 per carat.
To determine the price of a sapphire, four main criteria are examined, the famous 4C’s also valid for diamond estimation:
- The purity of the gem;
- The density of the color;
- The size of the stone;
- The use of treatments.
Where can I find sapphire?
Sapphires of Kashmir
Kashmir is an independent state located on the northern borders of India, Pakistan and China. Kashmir sapphires are famous for their “velvety blue” color. While production was abundant at the turn of the 20th century, it is almost nil and of poor quality at present.
The deposit was exploited from 11 881 to 1979. The mines are officially closed, but private exploitations operate under the control of the army.
These mines are located in the Zanskar valley.
These are the most prized sapphires (after the Burmese colors) for their aforementioned velvety blue color. However, apart from this characteristic color, here are some inclusions that allow us to recognize them:
- “Milky” zonations either straight or in chevrons;
- Tourmaline or zircon crystals;
- Amphibole fibers (pargasite);
Sapphires from Myanmar (formerly Burma)
Myanmar offers exceptional king blue sapphires and rubies called “pigeon’s blood”, these are the most appreciated colors, but the rarest. Most of the time sapphires have a very strong blue saturation and rubies a raspberry undertone.
The most prestigious region is Mogok. It was the arrival of the British in this region at the end of the 19th century that made the corundum of this valley known to Europe, as it became the property of the British crown.
Although there are always exceptions, Burmese corundum (Mogok type) is characterized by:
- Clouds of short, very dense silk
- Calcite and apatite crystals
- Syrupy zones
Sapphires from Sri Lanka (formerly Ceylon)
From ancient texts referring to trade between Rome and Sri Lanka, we know that the country has been supplying wonderful cornflower sapphires since antiquity, in addition to the exceptional colored sapphire called “padparadscha” meaning “lotus flower” in Sri Lankan (orange with a hint of pink). It is in the region of Ratnapura, the “city of gems”, that we find most of the Sri Lankan sapphires.
However, many sapphires come out of the mines and are called “geudas”, colorless to grayish and very included rutile. These are the sapphires that are most susceptible to heat treatment. Attention (!!!) all treatments are not bad.
Characteristic inclusions :
- Long rutile needles;
- Butterfly wing frosts;
- Color zonation.
Sapphires from Thailand (formerly Siam)
The first traces of corundum from the ancient kingdom of Siam date from the 15th century AD. Trade with European merchants flourished from the 16th to 18th centuries.
The corundum of Thailand is of magmatic origin and thus very ferrous which darkens them, they are thus considered of less good quality than the Burmese and cashmere. They come from the mines of Kanchanaburi (blue-gray sapphires), Chantaburi (rubies and dark sapphires) and Bo Ploi.
- Dark crystals like garnet, feldspars…
- Needles of boehmite
The mining area is located in the Anakie and New-England Range. This area began to be exploited in the early 20th century and reached its peak in 1970 in the early 90s, it represented 70% of the world market for sapphire.
Australian sapphires are also of magmatic origin and are recognizable by their very dark blue color due to the high presence of iron as well as their green zonations. They are then commercially nicknamed “wedding sapphire”.
Characteristic inclusions :
In addition to their fairly recognizable color, they can be recognized by their following inclusions:
- Tension halos and/or splintering rings
- Iron oxide needles
There are many other deposits such as Madagascar in the region of Ilakaka, which produces sapphires of very good quality and comparable to Kashmir sapphires (although all production is not declared and often sent to Thailand for treatment), Afghanistan, Vietnam …
Be careful not to confuse syntheses (crystals created in the laboratory) and treatments (human operations to improve the quality of a gem).
For the past twenty years, there has been a craze for unheated stones. Yet 90% of sapphires are heated. What does this mean?
In reality, most of these 90% are sapphires that are heated by hand at the mine exit. This process is called bata kubala or blow pipe and does not alter the structure of the gem; it just “pimps” the color. This treatment is not considered as such by the CIBJO, therefore it is not stated on the certificates.
When the term heated appears on the certificates, it refers to heat treatments that alter the structure of the gem. Generally practiced on geudas, this melts the inclusions causing them to darken the gem and therefore color it more. These treated gems can be recognized by heating stigmas in the gem.
Other treatments such as filling the fractures of the gem with glass are also to be considered, this treatment is called Glass filling. It is mainly applied to rubies.
Diffusion treatments, on the other hand, alter the structure of the gem in depth as well as its color.
If you are interested in sapphires, don’t hesitate to discover what Les Pierres de Julie offer in our store…
We are also available for any free expertise of your sapphire jewelry, for that you can send an email with your photos to firstname.lastname@example.org.