HOW TO CHOOSE A HIGH-QUALITY SAPPHIRE?
So you're looking for a sapphire, and you want to choose it correctly. With so many choices, and prices ranging from suspiciously low to ridiculously high, you might be wondering "How will I reconnaître un saphir de bonne qualité when I see one, and make the right choice in my purchase decision?"
At first glance, this may seem like the same thing as the "4 C's" when buying a diamond: Carat, Color, Clarity, and Cut, but this article will highlight the major differences between how diamonds and sapphires are graded, and therefore valued. Let's examine each of these steps, one after the other.
First step: color of the sapphire
This criterion comes first on the list for a good reason, as color is paramount with colored gems. So, for a blue sapphire, what shade of blue is the most desirable? The "superior" color is a saturated royal blue, that is, a deep bright blue with a violet hue.
What is the saturation of sapphire?
The Swiss Gemmological Laboratory defines saturation as: "A measure of the intensity or purity of a gem's hue or color. A gemstone that does not show any gray or brown hues is considered highly saturated and is more valuable than a gemstone with lower saturation." We like to think of a "juicy" color, elle will not seem pastel (white hue) or grayish (black shade).
Keep in mind that just because the industry says it's a "superior color" doesn't mean you shouldn't buy that "icy" blue, or that light violet blue that makes your heart sing. In fact, you'll pay less for lighter colors!
On the other hand, a sapphire that is too dark, like navy blue, is not desirable in the eyes of the gemstone industry. Except under the brightest light, the sapphire will not have any play of light and color, the sapphire will have a dull appearance.
It's important to know that almost all blue sapphires show some "zoning" of color under magnification, this is a specific characteristic of the sapphire.
What is the color zoning of sapphire?
In simple terms, it's the appearance of uneven color bands.
In reality, it's only a problem if the sapphire appears "striped" from the top view. The way the sapphire is set can help hide this zoning.
Obvious zoning in a sapphire detracts from its overall appearance.
If you like pink sapphires, they come in colors ranging from the palest pink to ruby red. Once they are red enough, they are considered rubies and not pink sapphires. They must also display a uniform color, whatever that color may be. There is no industry standard for the "ideal" color for pink sapphires, so it's a matter of personal preference!
Please note that if you are looking for Montana sapphires, they are judged on their own merits in terms of color, as they all have a gray background. Unlike the "velvet blue" of Ceylon sapphires, the color of a Montana blue sapphire will be more "denim", "stone", "lake", or "sky" blue. In addition to blue, Montana sapphires also come in many other colors.
Second step: the purity of the sapphire
Another very important difference between diamonds and colored gemstones lies in the way they are graded based on their clarity. First of all, unlike diamonds, colored gemstones are never graded as "flawless." The highest degree of purity that a sapphire - or any other colored stone - can have is "Eye Clean", also called "VVS" by some gemology labs, which means that inclusions are "very, very slight", usually undetectable to the naked eye. We will come back to the precise definition of "Eye Clean" in a minute.
Sapphires are considered Type II stones, which are "usually included."
What are the inclusions?
Inclusions are elements that have been trapped (or included) inside a gemstone during its formation in the earth. These "features" can be other minerals, liquids or gases. Some of these features are designated by self-descriptive names such as "rutile needles", "clouds", "fingerprints", "water lilies", "centipedes", "feathers" and "crystals", "frost", "bubbles"...
What is a "silk" type inclusion?
When extremely thin "inclusions" in the shape of a needle of the mineral rutile intersect, what is called "silk" is obtained and, under magnification, that's what it looks like, a fine weave of fabric. The silk interferes with the regular reflection of light, scattering it inside the stone.
Are inclusions related to poor quality?
All inclusions are like birthmarks that make each natural stone unique. Some types of inclusions provide proof that a sapphire is natural and not synthetic. Other inclusions may indicate whether a sapphire has been heated or not.
However, inclusions visible to the naked eye lower the value of a sapphire if they detract from their beauty. This can be due to their size, structure, an excessive amount of them, or if they reach the surface, resembling cracks.
What is an eye-clean sapphire?
This does not mean "nothing visible to the eye in any direction when looking as closely as possible." In the industry, this is the standard definition of eye cleanliness: When she is viewed by a person with normal 20/20 vision, at a distance of 10 to 12 inches, with the gemstone face up, under diffused lighting conditions, the gemstone will have no visible inclusions. 10 to 12 inches is roughly the distance between your eye and the top of a table when you are sitting, this is how gemstone dealers look at gemstone parcels. Face up would be the way a sapphire would be set in a frame.
Similarly, do not confuse a window with clarity, "Look, I can see through, it must be really clean." Windowing is a matter of cut, we will talk about it soon.
If you are looking for a pink or yellow sapphire (or any other color) and not a blue sapphire, the same guidelines regarding clarity apply.
Third step: the size or 'cut' of the sapphire
Yes, the cut is really important! There is a lot of science behind these little facets. To optimize the appearance of a sapphire, the cut must be made at the appropriate critical angles, taking into account the refractive index or the reflection of light specific to each gemstone. Many sapphires that are cut strictly for weight or diameter, will be off-kilter, or worse, will present extinction, or an unattractive window.
Extinction is just the difference in light reflection, and it's typical of oval, emerald and other elongated cuts. However, if, no matter how you turn it, elle seems dark or lifeless, that's extinction, the "dead spots" are what we call them, and it's usually a cutting problem. If the cutting angles were incorrect, the light would not be returned and reflected to the eye and the stone will look dead, extinguished.
Elongated shapes like rectangles, ovals, pears, and marquises often present what is called a "bow tie", that is, a darker or lighter reflection area in the pavilion. But this effect is not technically an extinction. It results from the fact that light is reflected to the eye at different speeds because not all sides are of equal length. Sometimes, facet experts can minimize or even eliminate this optical effect by making angle adjustments during the faceting process. Shapes such as rounds, squares or square cushions, and triangles usually do not present the bow tie effect.
What is a cutting window?
Can you see through the stone from the table to the culet, with facets and color seeming to be only around the edges? This is windowing, previously mentioned, which is caused when the pavilion angles (on the lower side of the stone) are cut lower than the critical angles required for that particular stone. Instead of bouncing light and reflecting it back to the eye, it passes through and continues on its way.
A poor cut will give an unattractive window.
A small window may seem to "close" when it is set, minimizing its appearance in the setting because there is no backlighting. When you have a good quality sapphire, but it has a small window, it may have been left that way to keep it at the desired carat weight. For example, instead of weighing "1.95 carats", leaving a small window could make it "2 carats."
Sapphires can be found in all different shapes, but they are most often cut round, oval, or cushion, as they maximize the natural shape of the raw material. A well-formed raw piece in the hands of a skilled cutter will only produce a third of its original weight if it is cut for its beauty and not just for its size.
The "brilliant cut", which was designed for diamonds, may suit lighter sapphires, but is generally not suitable for medium to deep colored sapphires. The sapphire has a different refractive index than the diamond and needs to be faceted to best bring out the color, as well as to maximize light reflection.
Other cutting issues that you should not see in a high-quality sapphire are chips, poor polishing, and distorted facets.
It is important that the sapphire you choose has been cut for its beauty, and not simply for its weight or diameter.
Can you see the difference between these two sapphires?
A native cut will be done to achieve maximum size and/or weight.
A properly cut stone will maximize the appearance of the stone's color and brilliance, with size and weight being a secondary consideration.
Fourth step: the carat weight of the sapphire
Weight is the last and perhaps the least important of the four Cs, in some respects. When it comes to sapphires, and all colored gemstones, the important measure is the size or "face-up" diameter, which is measured in millimeters, not the weight in carats.
A 1 carat round brilliant diamond will measure about 6.5 mm, as diamonds are cut at the same angle, with the same depth, most of the time.
As you just read in the "Cut" section, each gemstone has a different refractive index, which affects how light is reflected. A sapphire is denser than a diamond. It's like the elementary school riddle: "What weighs more, a ton of feathers or a ton of lead?" A ton weighs a ton, but the denser item will take up less space. So, while a 1 carat round brilliant diamond measures 6.5 millimeters, a round brilliant "roulette" cut sapphire, which also measures 6.5 mm, may weigh from 1.2 to 1.5 carats, but will fit the same 1 carat diamond setting. In other words, a 1 carat round sapphire may measure between 5.7 and 6 mm.
All this is not to say that carat size doesn't matter! Colored stones always have a price per carat, and the larger the sapphire, the rarer it is, the higher the price per carat will be. For example, if a 1 carat sapphire costs €1500, you might think that a 3 carat sapphire should cost three times as much, or €4500, right? Well... not really. A 3 carat sapphire that is just as well cut, clean, and of comparable color to the 1 carat stone will be so much rarer that it will probably be closer to €2500 per carat, or €7500 for the stone.
