Natural Sapphire Grading
Natural sapphires are graded and valued based on a few factors. These include sapphire color, sapphire clarity, and also their cut and carat weight. Even their country of origin is taken into consideration when determining their value. There are different grading systems used to determine the quality of this precious gemstone depending on what factor it’s being graded on.
Natural Sapphire Grading
With this system, sapphires are graded according to different ranks. These include AAA, AA, A, and B qualities:
- Natural AAA - This grade accounts for just 2% of all natural gemstones
- Natural AA - This grade represents 10% of all natural gemstones available in the world
- Natural A - This grade forms the top 20% of natural gemstones
- Natural B - This category accounts for over 50% of natural gemstones
Blue Sapphire Color
The most important characteristic to take into consideration when determining what a sapphire’s price is always its color grade. The very best color for natural blue sapphire is an intense, deep royal velvety blue. This color of sapphire would be considered AAA quality, they’re the most valuable, and the rarest. The second best color is a medium rich blue, which goes into the AA quality. Any blue sapphires that have a slight gray undertone fit into the A category. Finally, sapphires that have a very dark and opaque blue color are considered an B quality grade. The 3 keys to color grading are identifying hue, tone and saturation. Color is graded on these factors face up on a white surface. The hue should be royal blue, the tone should be deep blue and the saturation should be even throughout the gem.
Clarity Grading For Gemstones
After color, clarity is another important factor that has an impact on its price and rarity. There are three types of clarity grade for gemstones such as sapphires: Type 1 stones, Type 2 stones, and Type 3 stones.
- Type 1 stones - These stones will generally by eye clean. This means that they have no visible inclusions to the naked eye
- Type 2 stones - These typically do show some inclusions that are visible to the naked eye. However, they don’t take away from the overall beauty of the gemstone
- Type 3 stones - These gemstones will almost always have inclusions, and they will always be visible to the naked eye
Overall, most gemstones do have some type of inclusion, even if it isn't eye visible. Generally speaking, the fewer inclusions that a gemstone has, the rarer it is. Thus, the price will be higher for Type 1 stones compared to Type 3 stones.
Sapphires still fall into the general clarity grading for gemstones categories (Type 1 stones, Type 2 stones, or Type 3 stones). However, there are more specific and common terms that are directly related to the clarity of sapphires. These terms include: concaves, eye grade, loupe grade, and transparency.
- Concave - This is a natural mark that is found on the surface of sapphires. They normally form on the girdle, and they don’t interfere with the stones beauty
- Eye Grade - This evaluates the overall clarity of the sapphire when it’s viewed without any magnification, just with the human eye
- Loupe Grade - This is another form of evaluation, but differs from eye grade because here the clarity is checked under 10x magnification
- Transparency - Transparency is the relative ability that a sapphire has to transmit light
There are different types of inclusions that sapphires can have. Needles are long and thin mineral depositions in sapphires, which are referred to as silk inclusions. They are the most common type of inclusion. Silk inclusions form interactions within sapphire, and they are known to form the star effect. The price of sapphire drops when it contains more inclusions. This is because high amounts of inclusions affect the overall stability of the gemstone.
The cut of a sapphire refers to how well the surface is proportioned and polished. If a shallow or deep cut sapphire is poorly cut, it will be prone to light leakage. The best cuts of sapphire will always show optimal brilliance. They will look like they have more “life” to them. Sapphires that have cuts like this are rarer, and they are more expensive than inferior cut sapphires.
In terms of weight, sapphires are weighed the same way that diamonds are. The higher the carat, the more expensive the sapphire will be. Larger sapphires automatically have a higher carat weight, so they will always come with a higher cost.
Sapphire Treatments & Enhancements
The most common type of sapphire treatments is heat treatments. Heat treatments are applied to sapphires to remove inclusions and improve their color hue and saturation. This affects a sapphire’s color grade. It could be considered one specific grade before treatment, but then after treatment, it can jump up to a higher grade. Heat treatment is such a common procedure for sap-phires that it doesn’t affect their overall value. However, other treatments such as diffusion treatments (applying a thin layer of color onto the surface of a sapphire) can affect their value.
Understanding how sapphires are graded really helps when buying these gemstones. The very best grade of sapphire for jewelry would be Natural AAA, however, since this grade only accounts for 2% of all gemstones, it’s very rare and extremely expensive. The most common grade used for jewelry is natural AA, but natural AAA is also regularly used to create fine jewelry. When buying sapphires, it’s important to take the grade, color, clarity, inclusions, cut, and weight into consideration.Shop Sapphire Rings