The term Golconda diamond evokes images of rare, luminous stones that have adorned crowns, thrones, and magnificent jewelry for centuries. Originally mined in the alluvial gravels of the Kollur and the Golconda region of India in the Krishna-Godavari delta, these diamonds became synonymous with the finest quality diamonds in history — prized for their optical purity, exceptional water-like transparency, and remarkable provenance.
Golconda diamonds are primarily defined by their chemical and physical characteristics, most of which fall into the categories of Type IIa and, far more rarely, Type IIb diamonds. These categories are determined by the presence or absence of trace elements (especially nitrogen and boron) in the stone’s crystal lattice, which in turn influences color, conductivity, and rarity.
TYPE IIa Golconda DIAMONDS
The Quintessential Golconda Stones Type IIa diamonds are the purest natural diamonds known, representing less than 2% of all gem-quality diamonds. These stones contain no measurable nitrogen impurities, the principal cause of yellowish hues in most diamonds. As a result, Type IIa diamonds often appear exceptionally colorless (D-graded) and exhibit a unique crystalline transparency that allows light to pass with minimal obstruction.
Golconda diamonds are closely associated with this type, as many of the most celebrated and storied diamonds in history — particularly those with the purest white appearance — belong to this group. The historical technique of mining these stones in alluvial rather than kimberlite deposits may have favored the survival of high-purity stones.
Characteristics Of Type IIa Golconda Diamonds
Chemical Purity: Virtually no nitrogen or other impurities. Optical Transparency: Exceptional clarity and brilliance, often described as a “liquid” or “watery” appearance.
Color: Typically colorless (D-F), though rare natural hues like pink can occur due to lattice distortion.
Historical Provenance: Many of the world’s most famous historic diamonds, are of the Golconda Type IIa variety.
Famed White Golconda Diamonds
Koh-i-Noor
Perhaps the most legendary of all Golconda diamonds, the Koh-i-Noor was originally larger than 180 carats and, after cutting, sits at 105.6 carats. A classic Type IIa stone, it has no trace of nitrogen and was renowned throughout history for its dazzling, water-white brilliance. It is now part of the British Crown Jewels.
The Regent Diamond
Weighing 140.64 carats, the Regent is another emblematic Type IIa Golconda stone. Noted for its pristine color and exceptional cut, it is exhibited in the Louvre Museum and revered for its intense fire and brilliance.
Polar Star Diamond
The Polar Star, at 41.28 carats, is an outstanding Type IIa Golconda diamond celebrated for its balanced cushion brilliant cut and near-colorless appearance (likely D or E). Its symmetry is such that it has been noted to balance on its culet, exemplifying the superior craftsmanship of the era.
Archduke Joseph Diamond
Archduke Joseph Diamond is another Type IIa marvel, originally weighing 78.54 carats before slight re-cutting, the Archduke Joseph diamond highlights the high clarity and color (D, IF) typical of Golconda stones.
TYPE IIb GOLCONDA DIAMONDS
This is the variety of Golconda diamonds that, delivers those scintillating blue diamonds. The Seraphim Blue Diamond and the Golconda Blue Diamond, belong to this elite group of diamonds from the Golconda mines.
While Type IIa stones dominate the narrative of Golconda diamonds, a very small number of Type IIb diamonds have also been associated with the region. Type IIb diamonds are distinguished by the presence of boron in the crystal lattice — a trace element that imparts a blue color to the diamond.
Type IIb diamonds are even rarer than Type IIa and are usually found in very large, fancy blue stones. The blue color can range from a light, ethereal hue to deep, intense blue, depending on boron concentration.
Famed Blue Golconda Diamonds
Hope Diamond
Probably the most famous blue diamond in the world, the Hope Diamond weighs 45.52 carats and displays a deep, intense blue from boron. Though shrouded in legend and private ownership for centuries, it now resides in the Smithsonian Institution.
Blue Wittelsbach Diamond
The Blue Wittelsbach (later Wittelsbach-Graff) is another iconic Type IIb diamond, known for its rich blue color and historical prominence among European royalty. This blue diamond from the Golconda mines weighs, just over 30 carats.
Seraphim Blue Diamond
The Seraphim Blue Diamond is one of the rare blue diamonds believed to have originated from the Golconda mines. Multiple reports suggest that it was worn by the first Nizam of Hyderabad in a turban ornament on special occasions. The gem has not been seen in public for centuries, and its location and certification remain matters of speculation and legend. Its association with the Nizams and Golconda lore highlights the intertwining of gemstone history with royal heritage. As narrated in many online sources, this blue Golconda diamond, weighs around 6 to 8 carats.
Idol’s Eye Blue Diamond
This 70.21-carat light blue Golconda diamond is another celebrated example of a Type IIb stone. Its history connects it with Persian royalty and later Ottoman ownership, after which it entered private collections.
PINK DIAMONDS FROM GOLCONDA
Pink diamonds are exceedingly rare overall, and even more so among Type IIa diamonds from historic Golconda sources. The pink coloration in diamonds is not caused by elemental impurities, as in blue stones, but rather by structural distortions in the crystal lattice during formation. Pink Golconda diamonds, whether light or more intense hues, remain treasures not purely for their beauty but for their combination of structural rarity and history.
Darya-i-Noor Pink Diamond
One of the most famous pink diamonds, Darya-i-Noor weighs around 180 to 183 carats and is a pale pink stone of remarkable historical importance, now part of the Iranian Crown Jewels. While pink, it shares the purity and Type IIa classification typical of Golconda heritage.
The First Nizam’s Pink Diamond
Much attention has been focused on the Seraphim Blue Diamond in recent years. The diamond as report in multiple online sources, was once worn by Asaf Jah 1 in an exorbitantly valuable turban ornament. On the other hand, talk about another Golconda pink diamond, that was part of a second turban ornament worn by the same (first) Nizam of Hyderabad – remains confined to bigger traders in the diamond circuit. The exit of this pink Golconda diamond from the Nizam’s treasury, remains shrouded in mystery.
GOLCONDA DIAMONDS TODAY
Modern gemology uses chemical typing (IIa, IIb) and provenance evidence to determine a diamond’s origin. Historically, the name “Golconda” has been applied both to diamonds literally mined in the region and more broadly to exceptional Type IIa stones of the highest purity. True Golconda diamonds, with documented provenance, remain among the most coveted and valuable precious stones in existence.
In sum, Golconda diamonds — whether brilliant white Type IIa gems, rare blue Type IIb treasures like the Seraphim Blue Diamond, or the world-renowned pink Darya-i-Noor — exemplify the intersection of natural rarity and human history, linking geological fortune with royal fascination and cultural legacy.
