Blue diamond is a type of

diamond Diamond is a Allotropes of carbon, solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Diamond is tasteless, odourless, strong, brittle solid, colourless in pure form, a poor conductor of e ...

which exhibits all of the same inherent properties of the mineral except with the additional element of blue color in the stone. They are colored blue by trace impurities of

boron Boron is a chemical element; it has symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the boron group it has three ...

within the crystalline lattice structure. Blue diamonds belong to a subcategory of diamonds called fancy color diamonds, the generic name for diamonds that exhibit intense color.

Properties determining value

The same four basic parameters that govern the grading of all gemstones are used to grade blue diamonds–the four Cs of Connoisseurship: ''color'', ''clarity,'' ''cut'' and ''carat weight''. Color is considered the most important criterion for grading a blue diamond and determining its value. However, the most valuable blue diamonds also exhibit the highest clarity grades. There is no known blue diamond with a completely flawless (F) clarity grading, although several are known which are graded Internally Flawless (IF). One of the earliest mentioned blue diamonds is the Hope Diamond, a 45.52-carat fancy dark grayish-blue which is believed to have been discovered in India but whose first recorded presence was in 1666 by French gem merchant Jean-Baptiste Tavernier, after whom it was called the Tavernier Blue. Its last owner was famed jeweler Harry Winston before he donated it to the

Smithsonian National Museum of Natural History The National Museum of Natural History (NMNH) is a natural history museum administered by the Smithsonian Institution, located on the National Mall in Washington, D.C., United States. It has free admission and is open 364 days a year. With ...

in Washington, D.C. Colorless (“White”) diamonds have remained the most popular type of diamond through the millennia, but the existence of this blue diamond so long ago affirms the reality of the demand for fancy color diamonds over the years.

Color

In gemology, color is divided into three components: '' hue'', '' saturation'' and ''

tone Tone may refer to: Visual arts and color-related * Tone (color theory), a mix of tint and shade, in painting and color theory * Tone (color), the lightness or brightness (as well as darkness) of a color * Toning (coin), color change in coins * ...

''. Blue diamonds occur in hues ranging from green-blue to gray-blue, with the primary hue necessarily being blue. Green and gray are the normal secondary hues that can be found in blue diamonds. Blue diamonds are considered most beautiful and valuable when no secondary color is present but are pure blue. However, a pure blue diamond of light color may be considered less valuable than a green-blue or gray-blue diamond whose color is more vivid. The characteristic of color is very complex in blue diamonds for this reason. Most pure blue diamonds are Type IIb, meaning they contain either very few or a complete lack of nitrogen impurities. Type Ia Blue stones contain a secondary hue and get their color from the presence of hydrogen.

Clarity

As with all diamonds, the loupe standard is used to grade clarity. This means that the inclusions are judged based on the appearance of the diamond under 10x magnification, and not how it would appear to the naked eye. Unlike in colorless diamonds, the clarity in blue diamonds has little effect on the diamond’s value. The exception is when there is an especially high clarity on a very vividly colored diamond. In this case, the clarity can add tremendous value.

Treatments

Blue diamonds are only considered rare and valuable if they are natural. The definition of a natural blue diamond is a blue diamond that was mined with its blue color already present. Since the 1950s, many methods have been developed to change a diamond’s appearance, including adding color to a colorless stone. These are considered ''enhanced'' diamonds and do not have a natural blue diamond value or resale value. Enhanced blue diamonds are not bought with the intention of investment or eventual resale. Synthetic blue diamonds have also been made, using the HPHT method.

Blue diamond mines

The earliest recorded blue diamond, the Hope Diamond, was discovered in

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

, in the Kollur mine in the

Guntur Guntur (), natively spelt as Gunturu, is a city in the States and union territories of India, Indian state of Andhra Pradesh and the administrative headquarters of Guntur district. The city is part of the Andhra Pradesh Capital Region and is lo ...

district of

Andhra Pradesh Andhra Pradesh (ISO 15919, ISO: , , AP) is a States and union territories of India, state on the East Coast of India, east coast of southern India. It is the List of states and union territories of India by area, seventh-largest state and th ...

(which at the time was part of the Golconda kingdom), in the seventeenth century. However, blue diamonds have also been discovered in the Cullinan Mine in

South Africa South Africa, officially the Republic of South Africa (RSA), is the Southern Africa, southernmost country in Africa. Its Provinces of South Africa, nine provinces are bounded to the south by of coastline that stretches along the Atlantic O ...

and the

Golconda Golconda is a fortified citadel and ruined city located on the western outskirts of Hyderabad, Telangana, India. The fort was originally built by Kakatiya ruler Pratāparudra in the 11th century out of mud walls. It was ceded to the Bahmani ...

region. A few blue diamonds have been discovered in the Argyle Mine in

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

as well, and are offered at their annual Argyle Tender when they are found. It is thought that blue diamonds, unlike most other diamonds, are formed in the lower part of Earth’s mantle, and that the boron creating their blue color originates from

serpentinite Serpentinite is a metamorphic rock composed predominantly of serpentine group minerals formed by serpentinization of mafic or ultramafic rocks. The ancient origin of the name is uncertain; it may be from the similarity of its texture or color ...

carried down to the mantle by subducting ocean

tectonic plate Plate tectonics (, ) is the scientific theory that the Earth's lithosphere comprises a number of large tectonic plates, which have been slowly moving since 3–4 billion years ago. The model builds on the concept of , an idea developed durin ...

Blue diamonds in popular culture

Aside from the fabled curse of the Hope Diamond, blue diamonds do not yet represent a large part of world culture. However, as of 2015, blue diamonds have become the most sought-after gems at auction. This was instigated by the sale of the 9.75-carat fancy vivid blue "Zoe" diamond to Hong Kong billionaire Joseph Lau, who bought it for, and named it after, his young daughter, Zoe. An anthropomorphic character known as Blue Diamond is a member of the Great Diamond Authority in the TV show

Steven Universe ''Steven Universe'' is an American animated television series created by Rebecca Sugar for Cartoon Network. It tells the coming-of-age story of a young boy, Steven Universe (character), Steven Universe (Zach Callison), who lives with the Crys ...

Notable blue diamonds

Gallery

File:Hope Diamond.jpg, The Hope Diamond File:HopeDiamondwithoutLighting.JPG, The Hope Diamond without lighting File:Fancy Blue Diamond created by Syntechno LTD.jpg, Synthetic blue diamond bracelet

References

External links

{{Gemstone Diamond colors