Sapphire Grading Explained
When most people inquire about the grading classification of a sapphire, they expect that it will have a similar standardized system as diamond grading. Standardized grading of color, clarity and cutting has never been something that has been established on a uniform basis within the trade or within the various independent gemological laboratories.
There are many legitimate reasons why this is the case.
The basis is this: There are too many unique variables and subjective gradings within the realm of colored stones.
Diamonds for example, are not graded on tone, saturation or type of color - they are graded on the basis of not having any color. The baseline is colorless in diamonds. The diamond laboratories now use computer equipment that will electronically grade diamond color content against a baseline of colorlessness.
You can't do this with sapphires and other colored gemstones.
Colored stones are all about many characteristics of color:
- Color tone
- Purity of color
The problem is that color interpretation is always unique from one person to the next, so it is almost impossible to agree on a standard. Also, there are so many tones and hues of one type of color that identifying them all correctly on a standardized basis would be impossible.
On clarity, colored stones are generally far more saturated with inclusions at a level of 10 x magnifications than with diamonds. There are many different types of inclusions in colored stones as well. If the same clarity grading system were in place for colored stones as it is for diamonds, there would almost never be high-clarity graded colored gemstones.
This does not mean that all colored stones are included; rarely can you see inclusions without the support of magnification. Even in "included" colored stones it is difficult to see clarity issues without close inspection or with the aid of a loupe or microscope.
Cutting grading has similar complexity issues as clarity grading. The basic issue with grading cutting on colored gemstones is that there are so many types of cutting styles. It would be almost impossible to give a complete detail of a cutting style on each and every colored stone.
Demand for laboratory grading within sapphires and other colored stones has not reached a level where such a standardized system has been needed as of yet. If demand continues to rise for a standardized grading system it is possible that some perimeters will be established in a uniform code. In most cases an ideal grading should be done by a third party that has excellent experience within the field as well as no interest in the sale of the item being graded. But the bottom line is that there is currently no standardized
grading system. If someone tells you otherwise they are trying to sell you a service that is only reliable with that one person or company and not the general market.
The Bottom Line
What matters most in the end is how the sapphire appears to you. Below are the main points you want to review for "grading."
It must be pleasing to your eye. Whether it be blue, pink, yellow, Padparadscha,
or unique sapphire colors, this is the first priority in purchasing a sapphire.
Color is subjective, but usually on beautiful things most people agree. Something
with a good purity of color that shows well in all lighting conditions is what will
usually be in high demand, and hence cost more than a sapphire with mixed color
Treated sapphires cost MUCH less than stones that are untreated (they should if
you are buying from a reputable source). At The Natural Sapphire Company we only
try to offer 100% untreated sapphires. There are so many different types of treated
sapphires. If you would like to learn more about the many types of treatments please
refer to the Before and After Photos.
If you can see inclusions within the sapphire easily this will bring the value down.
If you can't see anything at all within the stone then this will be very rare,
as sapphires will almost always have some internal visual inclusions.
Below are a few terms relating to a sapphire's clarity:
Concaves/Naturals: natural indentations in the surface of a gemstone
created during crystal formation. These growth marks are usually found on the girdle
and do not affect the gemstone's beauty or luster.
Clarity, Eye Grade: an assessment of a gemstone's clarity
when viewed with no magnification.
Clarity, Loupe Grade an assessment of a gemstone's clarity
when viewed with 10x magnification.
Transparency: refers to a gemstone's relative ability to
Full light and color reflection is a very important part of a fine sapphire. A "window"
is a term used when the center of the stone is lifeless and has no color or light
reflection. A "window" will allow you to see through the backside of
the sapphire. Large windows should bring the price down in a sapphire, while a stone
with no window and full color and light reflection should increase the price.
The cutting process begins by selecting and sorting the various colors and qualities of the rough material.
Large inclusions are cut out of the rough sapphire for better inspection and analysis.
We pre-form our sapphire rough to the desired shape before we begin faceting the stone.
After we shape the sapphire rough, we attach it to a cutting pin with special wax for faceting.
Faceting a sapphire takes great talent and care. It takes decades to master this rare skill.
A beautiful cut transforms the rough crystal into an extremely fine stone.
Below are a few terms relating to 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: 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.
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: An assessment of a gemstone's cut based on its symmetry, windowing, extinction, brilliance, face-up cut grade, and profile cut grade.
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.
Zoning, or sometimes referred to as "color-zoning" is when the color intensity or color purity is not uniform throughout the sapphire. If you can see more color on one side but less on another side of a stone this should decrease the price.
The size of a sapphire will have a good amount of influence over its price vs. a smaller stone of similar attributes.
1-2 carat sapphires in fine quality are quite rare. Medium to lower qualities
are not very uncommon.
3-4 carat sapphires in fine quality are difficult to replace. Medium to lower qualities are available but not in large quantities.
5-7 carat sapphires in fine quality are very rare and almost impossible to match or replace. Medium to lower qualities are rare in this size as well.
8-10 carat sapphires in fine quality are one of a kind, no two stones are the same, reliable supply is not possible to maintain. Medium to lower qualities are rare and difficult to obtain as well.
10+ carat sapphires in fine quality are usually referred to as "Important" as they are always one of a kind, extremely expensive in blue, pink and rare colors. These stones are for the lucky and fortunate, not just the wealthy. Just to see these types of sapphires in person is referred to as a privilege.
The origin of a sapphire can have significant value determination. Sapphires have historical references in history and culture from particular locations that can weigh heavily on their values today. Burmese and Ceylon (Sri Lankan) sapphires have been characterized as fine sapphires in Europe for centuries, but Kashmir sapphires now have elite status, as they are no longer being found or mined.
A Major Note of Opinion from The Natural Sapphire Company on origin: With our excellent and thorough experience in working with sapphires and sapphire jewelry we have determined that origin cannot be conclusively decided in sapphires. We offer fine quality untreated sapphires so we understand them very well. We do not put value on a sapphire based on the "origin" of the stone. It is our experience that FAR too many inconsistencies and crossover identity issues exist between all sapphires, making it almost impossible to definitively state the origin of a sapphire.
Many (if not all) laboratories will tell you that they can in fact determinethe origin of sapphires, but it is our experience that they are NOT consistent andreliable results. One very prominent and famous laboratory, the GIA (Gemological Institute of America) does not offer origin determination on sapphires. While they may not state why they do not offer this service; it is our conclusion that they do not want to report on things that cannot actually be reported on. If you look at the disclaimer on most laboratory origin reports they do not accept liability for results on origin determination. If a laboratory certifies a sapphire as a "Kashmir" origin the stone is worth 10 times its value if it is from another origin. This extreme price difference does not make sense if so many flaws on origin reporting exist.
The Natural Sapphire Company does not recommend or advocate spending premiums for stones based on origin determination from a laboratory. We specify the origin of our sapphires in our listings. These are based on our supplier and mine location where we know the sapphires originated. Determining if a sapphire has been treated or not is usually very easy and we highly recommend only purchasing sapphires that are untreated. Since we have found so many inconsistencies on origin determinations we no longer purchase sapphires or sell sapphires with a price based on origin status from a laboratory report. What is truly naturally beautiful and rare is valuable.