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- Natural AAA – Represents only 2% of all natural gemstones
- Natural AA – Covers 10% of all natural gemstones globally
- Natural A – Includes the top 20% of natural gemstones
- Natural B – Constitutes over 50% of natural gemstones
Blue Sapphire Color
The foremost characteristic in determining a sapphire’s value is its color grade. The optimal hue for a natural blue sapphire is a rich, velvety, deep royal blue, classified as AAA quality and considered the rarest and most valuable. The next best color is a medium-rich blue, categorized as AA quality. Blue sapphires with a slight gray undertone fall under the A category, while the very dark and opaque blue ones are classified as B quality. The three key factors in color grading are hue, tone, and saturation, all evaluated on a white surface. The hue should be royal blue, tone a deep blue, and saturation even throughout the gemstone.
Clarity Grading For Gemstones
Besides color, clarity is another significant factor influencing a gemstone’s price and rarity. Sapphires can have three types of clarity grades: Type 1, Type 2, and Type 3.
- Type 1 stones – Typically “eye-clean” with no visible inclusions.
- Type 2 stones – Often show some inclusions visible to the naked eye but remain aesthetically pleasing.
- Type 3 stones – Usually have visible inclusions.
Most gemstones have some type of inclusion, though they may not always be visible. Generally, fewer inclusions make a gemstone rarer and more expensive, thus Type 1 stones are priced higher than Type 3.
Sapphires adhere to the general clarity grading categories (Types 1, 2, or 3), but also have specific terms related to clarity, such as concaves, eye grade, loupe grade, and transparency.
- Concave – A natural mark on the surface, commonly found on the girdle without affecting beauty.
- Eye Grade – Evaluates clarity when viewed without magnification.
- Loupe Grade – Clarity assessed under 10x magnification, differing from eye grade.
- Transparency – Measures the gemstone’s ability to transmit light.
Sapphires can have various types of inclusions, such as silk inclusions (long, thin mineral deposits), which can cause the “star” effect when interacting within the stone. Increased inclusions decrease a sapphire’s value as they affect stability.
Sapphire Cut
The cut refers to how well a sapphire’s surface is proportioned and polished. Poorly cut sapphires may leak light if too shallow or deep. The best cuts exhibit optimal brilliance, appearing more “alive” and are rarer and more expensive.
Carat Weight
Sapphires are weighed in the same manner as diamonds. Higher carat weight increases a sapphire’s price. Larger sapphires inherently possess higher carat weights, leading to greater costs.
Sapphire Treatments & Enhancements
Heat treatments are the most common methods for removing inclusions and enhancing hue and saturation in sapphires. This treatment can elevate a sapphire’s color grade but does not affect overall value. Conversely, diffusion treatments, which apply a thin color layer to the surface, can lower a sapphire’s value.
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