LAREINE Diamond Encyclopedia
Natural Blue Diamonds
From pale ice blue to deep ocean tones, natural blue diamonds unite extraordinary geological conditions with exceptional rarity.
Natural blue diamonds possess a blue hue created within the crystal through rare geological processes. Their colors can range from cool gray blue and pale sky blue to highly saturated blue.
Most natural blue diamonds owe their color to extremely small amounts of boron incorporated into the carbon crystal structure. Boron changes the way the diamond absorbs visible light, allowing blue to become the dominant color perceived by the eye.
Boron and Type IIb Diamonds
Many boron bearing natural blue diamonds belong to the Type IIb category. They contain very little nitrogen and may exhibit electrical conductivity, an unusual property among natural diamonds.
A link to ancient oceans
Research indicates that boron rich material from Earth’s surface may have been carried deep into the mantle by tectonic processes before becoming incorporated into certain blue diamonds.
More than one cause
Not Every Natural Blue Is Created the Same Way
Boron is the principal cause of natural blue, but gemological laboratories encounter several less common mechanisms that can produce blue related colors.
01
Boron
The primary cause of pure to grayish blue in many Type IIb natural diamonds.
02
Natural radiation
Changes to the crystal lattice can create a greenish blue appearance in some natural diamonds.
03
Hydrogen
Hydrogen related defects may contribute to gray violet through gray blue colors.
04
Light scattering
In rare cases, microscopic inclusions can scatter light and create a blue appearance.
Historically important blue diamonds came from India’s Golconda region. In modern times, South Africa’s Cullinan mine has produced several exceptional stones. Occasional discoveries have also occurred elsewhere, but fine natural blue remains exceedingly scarce.
Color classification
Understanding Blue Diamond Grades
GIA evaluates blue diamonds through hue, tone and saturation. Because strong saturation occurs only rarely in natural blue, even comparatively light stones can be important.
Faint
Very Light
Light
Fancy Light
Fancy
Fancy Intense
Fancy Vivid
Fancy Deep
Fancy Dark
Illustrative scale only. Screen colors cannot reproduce controlled laboratory conditions or the optical behavior of a diamond.
Fancy Vivid combines strong saturation with a tone that allows the blue to remain highly visible. Fancy Deep and Fancy Dark describe different combinations of tone and saturation, not simply grades above Fancy Vivid.
Reading the color name
Pure Blue and Modifying Hues
The final color named on a laboratory report is the dominant hue. A modifier can change the character, rarity and market preference of the diamond.
Blue
An unmodified blue grade. Strong pure blue with attractive tone and even distribution is exceptionally rare.
Grayish Blue
Blue remains dominant, while gray gives the color a cooler and more subdued character.
Greenish Blue
Blue remains dominant, while green produces a more teal or oceanic appearance.
Optical design
How Cut Influences Blue Color
Blue diamonds are cut to balance color presentation, brilliance, proportions and retention of valuable rough weight. They do not receive a formal GIA cut grade, but polish and symmetry remain important.
01
Emerald cut
Broad facets can reveal transparency, depth and calm flashes of blue in suitable material.
02
Cushion and radiant
Mixed faceting can concentrate face up color and distribute it across the stone.
03
Pear and oval
Elongated outlines can preserve weight while creating strong visual presence.
04
Color zoning
The cutter must minimize distracting pale areas and dark zones while maintaining life.
Jewelry setting
Cool white metal and colorless diamonds can create crisp contrast around blue. A setting changes visual perception but does not alter the laboratory color grade of the loose diamond.
Quality factors
What Determines Rarity and Value?
- Color
Hue, tone and saturation have the greatest influence. Strong, attractive blue with minimal modifier is particularly sought after.
- Modifier
Gray or green can produce beautiful stones, but pure blue generally occupies the highest rarity category.
- Distribution
Even face up color is usually preferred to obvious zoning, pale windows or excessive extinction.
- Carat weight
Most natural blue diamonds are small. Size has a dramatic effect when combined with strong color and high transparency.
- Cut
A successful cut preserves scarce material while revealing color, brightness and balanced proportions.
- Clarity
Color remains dominant, but inclusions affecting transparency, beauty or durability can reduce value.
LAREINE expert guide
How to Select a Blue Diamond
The report identifies the grade and color origin. Final selection should also consider how the blue behaves as the diamond moves through different lighting.
Compare stones under consistent lighting.
Check whether blue remains visible across the face.
Evaluate brightness as well as saturation.
Study gray or green modifiers carefully.
Review transparency and dark extinction.
Confirm natural color origin independently.
Certification
Confirming Natural Blue Color
Blue color can occur naturally, be created in a laboratory or result from treatment of a natural diamond. Irradiation and HPHT processes can produce or alter blue related colors, and appearance alone is not a reliable test.
A GIA Natural Colored Diamond Report identifies whether the diamond is natural and whether its color is natural or treated. Depending on the service, it can also include the complete color grade, clarity, carat weight and identifying characteristics.
The LAREINE Perspective
An important natural blue diamond should possess more than depth of color. The blue must remain alive within the stone, supported by transparency, balanced distribution and a cut that allows light to move naturally.
At LAREINE, each important blue diamond is selected individually, with close attention to natural color origin, modifying hue, cut, rarity and gemological certification.
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