Sapphires: Grading, Colour, Cut, and Carat Weight
The grading and valuation of natural sapphires are determined by several factors such as their color, clarity, cut, carat weight, and country of origin. Various grading systems are used to assess the quality of this precious stone based on the specific factor being evaluated.
One such system involves grading sapphires on a scale of AAA, AA, A, and B, with each grade representing a different rank. For instance, natural AAA grade is exceedingly rare, comprising only 2% of all natural gemstones. On the other hand, natural B grade is the most common, accounting for over 50% of all natural gemstones. The higher the grade, the more valuable the sapphire is considered.
Blue Sapphire Color
When determining the price of a sapphire, the most significant factor to consider is its color grade. For natural blue sapphires, the ideal color is an intense, velvety, deep royal blue, which is classified as AAA quality and is extremely rare and valuable. The next best color is a medium rich blue, which is classified as AA quality. Blue sapphires with a slight gray undertone fall under the A category, while those with a very dark and opaque blue color are considered B quality grade.
To assess the color of a sapphire, three essential elements must be considered: hue, tone, and saturation. These factors are evaluated by examining the sapphire on a white surface from a face-up perspective. The hue of the sapphire should be royal blue, the tone should be deep blue, and the saturation should be uniform throughout the gem.
When it comes to gemstones like sapphires, clarity is another critical factor that affects their rarity and price, following color. Gemstones are generally classified into three clarity types: Type 1, Type 2, and Type 3.
Type 1 stones are typically "eye-clean," meaning they have no visible inclusions to the naked eye. Type 2 stones may have some inclusions that are visible to the naked eye, but they don't significantly affect the gemstone's beauty. Type 3 stones almost always have visible inclusions that affect the overall clarity of the gemstone.
While most gemstones have some level of inclusion, even if it's not visible to the naked eye, the rarer a gemstone is, the fewer inclusions it has. Consequently, Type 1 stones are rarer than Type 3, and their prices are higher.
Regarding sapphires specifically, there are other terms used to evaluate their clarity, such as concaves, eye grade, loupe grade, and transparency. Concaves refer to natural marks on the surface of the sapphire that don't detract from its beauty. Eye grade and loupe grade evaluate clarity with and without magnification, respectively, while transparency refers to the gemstone's ability to transmit light.
Sapphires may have different types of inclusions, with silk inclusions, also known as needles, being the most common. These inclusions can form interactions within the sapphire, creating the "star" effect. As the number of inclusions increases, a sapphire's stability and overall value decrease.
Sapphire Cut and Carat Weight
When discussing sapphire cut, it refers to how well the surface has been proportioned and polished. Poorly cut sapphires that are either too shallow or too deep may have light leakage. Optimal brilliance is achieved in the best cuts of sapphire, which appear to have more "life" to them. These cuts are rarer and more expensive than inferior ones.
Sapphires are weighed similarly to diamonds, and their weight is measured in carats. The higher the carat weight, the more expensive the sapphire will be. Since larger sapphires have a higher carat weight, they tend to cost more.
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