Sapphire Facts

The name Sapphire come from the Greek word for blue, although in the middle ages the name was applied more to what we know today as Lapis Lazuli. Back then, the ancient civilizations never expected this unique gems stone, to come in such a vast array of colors!

Sapphire and Ruby are members of the  Corundum family. If Corundum exhibits a colour from slightly pinkish red, through red to slightly reddy brown then it is called a Ruby.

All other colours of Corundum are termed Sapphires.

So while we traditionally think of Sapphires as being only blue stones, they actually come in all colours from black to white.  

Untreated sapphires make up less than 1% of gems available on the market.

What makes this gem even more unique is that Corundum is second only to Diamond in terms of its physical hardness, (although exhibiting only  1/140th of the hardness of Diamond), this hardness (9 on the Moh's scale) in relation to all other gemstones has ensured Sapphires position with Ruby being the go to choice in longevity gems. 

Sapphire is also known as a precious gem stone, making it one of the “big four” Gems (diamond, rubies, emeralds and sapphire)

Sapphire is the birthstone for those whose birthday falls in September, and for those born under the star sign of the Taurus.

Natural vs Treated 

Both natural and treated  sapphire are natural sapphires. The distinction is actually referred to as Untreated vs Treated.

When considering sapphires in particular, understanding the terms “natural” and “untreated” are crucial to making an educated decision. Many people confuse natural for meaning untreated, and vice versa. In optimal circumstances, both terms should apply to the gemstone, but that is rarely the case with what is currently in the market.

In very short detail, an untreated sapphire is one that has been taken from the ground and then faceted. Nothing at all was done to the stone to alter the natural beauty, which only elements and process in the earth created naturally. These sapphires are exceptionally more rare and valuable. For this reason, sapphires are extraordinarily unique from one to the next.

The word “natural” identifies a sapphire crystal that has been developed in the ground, not synthetically created. The word  “untreated” means that a natural sapphire has not undergone any heat or chemical treatments to improve its color or clarity.

“Natural” does not mean the sapphire has not undergone any alterations. The key term is “untreated,” meaning a sapphire is natural (not lab created) and has not been subject to any chemical or heat treatments. Approximately only 0.5 - 1% of the sapphires discovered are of gem quality without treatment. Natural untreated sapphires are far more uncommon and valuable than treated and chemically altered stones.

Sapphire - Common Treatments

Heat Treatment
Sapphire like their cousins Rubies are commonly heat treated to enhance their colour and to even out or totally remove "silk". While initially only stones of a lower quality were treated in this way, estimates indicate that heating is now carried out of about 95% of all rough material, as part  of an industry accepted enhancement technique. Heat treatment is used specifically to improve and even out the colour in Sapphires, and when done at a moderate heat will reduce the presence of needles. At higher temperatures needles, specifically of Rutile are completely removed by a process of melting and re absorption. These heat treatments enhancements  typically occur around temperatures of 500  - 1800 °C, in computer controlled electric furnaces. Some cutting houses still use the older process of low tube heat, when the stones are heated over charcoal at a temperature of about 1300 °C  for 20 to 30 minutes, a process know in the trade as "Chanthaburi cooking". The silk is only partially broken as the color is improved, imbibing the stone with a richer luster, and better colour.

Diffusion Treatment
The diffusion technique is essentially a method of coating a natural Sapphire with a "skin" of colour. The compound for diffusion is effectively bonded into the outer layer of the cut stones as they approach their melting point, thus forming a composite lay of essentially Sapphire and the diffusion agent on the stones surface. The depth of this colour enhanced skin can vary  from a few microns to an millimeter or more depending on the method used. Initially this was confined to blue Sapphires of a lower blue or  green colour, and the diffusion coating was Titanium oxide, which imparted a deep blue colour to the stones. Recently Beryllium is being diffused into the surface of  fancy yellow and pink sapphires at very high heat, and again close to their melting point.  This process  produces stunning red and orange colours that are only rare and expensive in nature (Padparadscha).

Natural vs Synthetic vs Simulated 

High value gemstones are mostly unobtainable to the average person.  The desirability of these cherished pieces created a demand for identical looking imitation gemstones. 

The issue we face is that both simulated and synthetic gems are laboratory-grown gemstones.

Deceitful sellers can often try to swindle even the most experienced buyer. 

There two main distinction between synthetic and simulated gemstones: 

  1. One resembles the real deal - based entirely on physical appearance
  2. One bears the identical properties of the real deal and in actual fact is the real deal

The sad part is that depending on how these replica gemstones are marketed, many fall for simulated (the imitation of physical appearance) as the real lab made alternative. Real Lab Made gems are identical in composition to the earth mined counter part. 

Real Sapphire created in a laboratory is called “synthetic sapphire”

Synthetic (laboratory-grown) gemstones

These gemstones are identical in composition to their natural counterparts in every way; the only difference is that they are created in a laboratory. These synthetic gemstones are often labeled as “laboratory grown” or “laboratory created”, words which are more acceptable to a buyer than “synthetic”.  As synthetic gemstones can be made , they are not rare and their prices and quality do differ due to the different manufacturing methods.

Simulant (imitation) gemstones

Imitation gemstones that do not have the same properties as natural gemstones but resemble the natural gemstone they imitate are called simulants. A simulated gemstone can be any material that takes on the appearance of a natural gemstone.  The most popular diamond simulant is cubic zirconia which has enjoyed a two decade stronghold over other simulants.  

Cubic zirconia is an inexpensive diamond simulant and an excellent alternative to diamond due to its high optical properties and good brilliance. Although mostly seen in its white or colorless forms, it is also available in a wide variety of colors.

At Sapphire South Africa, we do retail synthetic sapphire based on budget requirements. As a synthetic (being the real deal in composition) , we feel that it far outweighs the (cubic) or the simulated versions available for the lower end budgets. Not only do we feel that the synthetic sapphires are better in terms of gem nature (composition), they are also harder and better all round gem stones than your average simulant in the market! 

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4Cs of Sapphires?

Similar to diamonds, the quality of colored gemstones is graded using standards set for four criteria. We use the 4Cs for sapphires below for a complete guide on how color, clarity, cut, and carat weight affect sapphires. 

COLOUR

Color interpretation is unique from one person to the next. Lighting may also affect the appearance of color. We always do our best to give our sapphires the most accurate color classifications. We evaluate our sapphires in extreme detail, and the resulting color description is based on our professional opinions.

Judging of a sapphire’s color is dependent on three prevailing factors: the gemstone’s hue, saturation, and tone.  Often, multiple colors can be found in the same sapphire.

Hue is the gemstone’s basic color.  While a sapphire’s color might be described as yellow or blue, more often gems are a combination of hues.  For example, a blue sapphire can have violet or green secondary color components that affect their beauty and value.  The hue of these sapphires would be more accurately described as violetish-blue or greenish-blue.

Tone, which describes how light or dark a stone’s color is, will also influence a sapphire’s value.  The preferred tones for sapphires vary from hue to hue, but most fine sapphires have a medium to medium-dark tone.  For example sapphires that have a very dark tone are often described as “inky.”

Saturation describes how pure or intense a color appears, and it is a key component in determining a sapphire’s value.  The color of a sapphire may be “diluted” with what is called a “saturation modifier.”  With cool colored sapphires like blue, green, and violet, gray is the usual saturation modifier.  

With warm colored sapphires, including yellow, red, and orange, the typical saturation modifier is brown. Regardless of the sapphire’s hue, higher levels of saturation are preferred, which means modifiers do not dilute their color.  The finest sapphires have “vivid” saturation, but sapphires with “strong” saturation are also prized.

CLARITY

The clarity of a sapphire begins to develop at the very earliest stages of its creation. Sapphires form under very specific conditions within the earth’s crust. They can take centuries to form through the process of the presence of corundum in igneous rock that slowly cools and changes over time.

As these formations are cooling, large crystals of minerals can form from what is present within the magma. The more slowly the cooling occurs, the larger the sapphire will grow. The conditions under which magma cools are very likely to introduce changes in pressure and environmental factors that produce inclusions in the sapphires.

The presence of these inclusions and trace minerals create the unique color and overall look of each colored gemstone. As a result, each sapphire is truly unique and no two will ever be the same or have the exact same internal structure.

In order to judge the clarity of a sapphire, the size, location, quantity, and overall appearance of inclusions are of the greatest importance. Inclusions can affect the sapphire’s beauty and brilliance in both positive and negative ways, to it’s imperative to understand inclusions. For that reason, we have a more extensive discussion of inclusions on our site.

While diamonds are valued for their lack of inclusions, all of gemstones are expected to have a certain amount of inclusions as a result of their natural crystal growth. When evaluating clarity for a sapphire, the grading of “eye-clean” is the optimal clarity, meaning no inclusions are visible to the naked eye.

“Eye-clean” sapphires are extremely rare and valuable, especially when even the finest gemstones are not expected to be free of inclusions even when viewed under 10x magnification. For that reason, even gradings that are “very slightly included” or “slightly included” will be beautiful gemstones.

CUT 

The term “cut” can have several meanings when applied to sapphires and other gemstones.  For example, it may describe the faceting style or shape of a finished gemstone. The term also refers to a gemstone’s proportion and finish.

Proportion refers to the rough dimensions and overall symmetry of a gemstone.  Finish describes the precision with which facets meet, the relative size and number of facets, and the quality of the stone’s polish.

sapphire cut grade diagram

 
A diagram showing the overall cut grades for sapphires.

Like most transparent gems, sapphires reveal their full beauty when they are cut.  However, because sapphire rough is so valuable, dealers and consumers accept gemstones without the precision cuts required of fine diamonds.  In general, gem cutters follow four guiding principles when they fashion sapphires:

  1. Maximize the apparent color of the gem. A skilled gem cutter can influence the apparent color of the stone by maximizing a stone’s brilliance or amount of light returned to the viewer’s eye.
  2. Maximize the gemstone’s final weight.  This may be constrained by the sapphire’s crystal habit or growth-form.
  3. Minimize the appearance of undesirable inclusions or color zoning.
  4. Filling consumer demand for certain fashions or cutting styles.

The following are terms that help explain the elements of a cut:

Symmetry Grade: an assessment of a gemstone’s proportion, balance, and uniformity determined by a number of criteria including length-to-width ratio, bilateral mirror images, etc.

face-up cut grade diagram

 
Face-up cut grade diagram.

Face-Up Cut Grade: an evaluation of a gemstone’s symmetry, proportion, and appeal while viewing the stone with its table facing the viewer.

Profile Cut Grade: an evaluation of a gemstone’s symmetry, proportion, bulge, table size, and girdle thickness while viewing the stone from the side.

Profile cut grade diagram

 
Profile cut grade diagram.

Table Size: is calculated as a percentage of the gemstone’s total width. The table is described as small if its size is under 33%; acceptable if it is 33-67%; and large if it is above 67%.

Girdle Thickness: the average thickness of the gemstone’s girdle, which is the junction between the crown and pavilion of the stone.

Overall Cut Grade: Overall Cut Grade: an assessment of a gemstone’s cut based on its symmetry, windowing, extinction, brilliance, face-up cut grade, and profile cut grade.

window pink sapphire

 
An example of a window and extinction in a cut and faceted pink sapphire.

Window: an area in a transparent gemstone where the body color appears to be see-through or watery. This occurs when the crown or pavilion angles are cut shallowly, causing light to leak out of the pavilion.

Brilliance: the amount of light that a cut gemstone reflects back to the viewer from the interior of the stone. Brilliance is a consequence of cut and it is an important characteristic because it determines the perceived liveliness and color of a gemstone.

Extinction: an area of a transparent gemstone where the body color looks very dark to black. This occurs when gemstones are cut with excessively deep pavilions.

CARAT 

Large gemstones are harder to find than smaller ones.  The effect of carat weight upon sapphire value varies from color to color.  Yellow sapphires are comparatively plentiful in sizes above five carats, but five-carat padparadscha sapphires are extremely hard to come by.  

As with any gemstone, per carat prices increase with overall carat weight.  Expect steep increases in the price per carat at the one, three, five, and ten-carat levels.  Fine blue, pink, orange, or padparadscha sapphires that exceed fifteen carats are especially valuable and can fetch very high prices at auction.

Fine quality sapphire rough is extremely expensive, so quality stones are not usually cut to calibrated sizes because it could result in a significant loss of weight.  Commercial quality sapphires are more likely to conform to standard calibrated sizes.

A sapphire’s size, if expressed in a unit of weight, is called a carat (abbreviated “ct”).  A carat is a metric unit equivalent to one fifth (.20) of a gram.  One hundredth of a carat is called a point (abbreviated “pt”).  A number of small sapphires may be weighed together to give a total carat weight (abbreviated “tcw”).  Because sapphires have a high specific gravity, a one-carat sapphire will appear smaller than a one-carat diamond.

Credits: Natural Sapphire Company

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