Gabriel Tolkowsky, born in Antwerp in 1939, stands among the most accomplished diamond cutters of the twentieth and twenty-first centuries. A fifth-generation member of the Tolkowsky family — one of the most distinguished dynasties in the history of diamond cutting — he is best known for his work on two of the most celebrated diamonds in recorded history: the 273.85-carat Centenary Diamond and the 545.67-carat Golden Jubilee Diamond, the largest faceted diamond in the world. His career represents a rare synthesis of inherited craft knowledge, rigorous optical science, and an artist's sensitivity to the individual character of each stone.

The Tolkowsky Dynasty

To understand Gabriel Tolkowsky's significance, one must first appreciate the lineage from which he descends. The Tolkowsky family's association with diamond cutting spans at least five generations, rooted in the Antwerp and later the broader European diamond trade. The family's most celebrated intellectual contribution came in 1919, when Marcel Tolkowsky — Gabriel's great-uncle — published Diamond Design: A Study of the Reflection and Refraction of Light in a Diamond, a treatise that applied mathematical and optical analysis to determine the proportions that would maximise a round brilliant diamond's brilliance and fire. Marcel's calculations underpinned what the trade came to call the "ideal cut" or "American ideal cut," and they remain a foundational reference in modern diamond grading.

Gabriel grew up immersed in this tradition. He trained in Antwerp, then the undisputed world centre of diamond cutting, absorbing both the technical rigour and the tactile intuition that distinguish a master polisher from a competent one. By the time he was entrusted with the most consequential diamonds of the late twentieth century, he had decades of experience working with exceptional rough, and had developed a reputation for patience — a willingness to study a stone for months before committing a single facet.

The Centenary Diamond

The Centenary Diamond was recovered from the Premier Mine (now Cullinan Mine) in South Africa in July 1986, weighing 599 carats in the rough. De Beers announced its existence publicly in 1988, at the company's centenary celebrations — hence the name. The rough was described as the largest known diamond of top colour (D, in GIA terminology) and internally and externally flawless clarity. Its significance was therefore not merely one of size but of quality: a stone of this mass at this grade of colour and clarity was, and remains, without parallel in documented gemological history.

De Beers entrusted the cutting to Gabriel Tolkowsky. He was given a specially constructed underground laboratory beneath the De Beers offices in Johannesburg, where temperature, humidity, and vibration could be controlled. Before any cutting began, Tolkowsky spent approximately three months studying the rough — mapping its internal structure, identifying inclusions and grain directions, and modelling how light would behave within different proposed forms. This preparatory phase was not merely cautious; it was methodologically essential. A single miscalculation on a stone of this rarity could have reduced its value by tens of millions of pounds.

The cutting process itself took roughly three years, from 1988 to 1991. Tolkowsky ultimately fashioned the rough into a modified heart shape with 247 facets — far exceeding the 58 facets of a standard round brilliant. The finished stone weighed 273.85 carats. The additional facets were not decorative excess; each was calculated to manage the stone's optical behaviour, compensating for the asymmetries inherent in a heart-shaped outline of this scale. The result was a diamond of extraordinary brilliance and internal fire, exhibiting the kind of light performance that only becomes possible when a cutter of Tolkowsky's calibre works in concert with a stone of this quality.

The Centenary Diamond was exhibited publicly for the first time at the Tower of London in 1991. It has been valued at over 100 million US dollars, though as an uninsured stone held by De Beers, its precise current valuation is not publicly disclosed. It remains one of the most technically complex cutting achievements in the history of the craft.

The Golden Jubilee Diamond

If the Centenary Diamond represents the pinnacle of colourless diamond cutting, the Golden Jubilee represents Tolkowsky's mastery of fancy-colour material. The rough from which the Golden Jubilee was cut was also recovered from the Premier Mine, in 1985 — the year before the Centenary rough was found. It weighed 755.5 carats in the rough, making it the largest rough diamond recovered from the Premier Mine at that time.

The rough was initially used as a test stone — a vehicle for experimenting with new cutting techniques and tools — before its full potential was recognised. Tolkowsky was again engaged to cut the stone, working under the auspices of a Thai businessman, Henry Ho, who ultimately presented the finished diamond to King Bhumibol Adulyadej of Thailand in 1997, to mark the fiftieth anniversary of the King's accession — the Golden Jubilee of the stone's name.

The finished Golden Jubilee weighs 545.67 carats, making it the largest faceted diamond in the world by weight, surpassing even the Cullinan I (Great Star of Africa) at 530.20 carats. Its colour is described as fancy yellow-brown, a warm, cognac-like tone that Tolkowsky enhanced through the cutting process by carefully orienting the facets to deepen and enrich the natural body colour. The form is a fire-rose cushion cut, a shape that Tolkowsky developed specifically for this stone, with 148 facets arranged to maximise the interaction of light with the stone's colour.

The Golden Jubilee was blessed by a Buddhist supreme patriarch and a Catholic cardinal before being presented to the King, and it is now part of the Thai Crown Jewels. Its official value has been cited at approximately twelve million US dollars, though this figure reflects a formal valuation for ceremonial purposes rather than a market assessment of a stone that is, in practical terms, without comparable precedent.

Technique and Philosophy

What distinguishes Tolkowsky's approach from that of most commercial cutters is the degree to which he treats each stone as an individual optical problem rather than a candidate for a standard form. Commercial diamond cutting — even at the highest levels — tends toward optimising yield from rough within well-established shapes and proportions. Tolkowsky's work on the Centenary and Golden Jubilee required the opposite: the shape was determined by the stone, not imposed upon it.

His method integrates several disciplines. He employs advanced optical modelling — computer-assisted ray-tracing and light-performance simulation — to predict how a proposed facet arrangement will behave before any physical work begins. This modelling is then tested against his own empirical knowledge of how diamonds actually behave under the polishing wheel, knowledge that cannot be fully encoded in software. The interplay between computational prediction and manual refinement is central to his practice.

Tolkowsky has also spoken and written about the psychological dimension of working with exceptional rough: the necessity of patience, of resisting the temptation to begin cutting before one truly understands the stone. This is not mysticism but practical wisdom. On a stone worth tens of millions of pounds, the cost of a premature decision is catastrophic and irreversible.

His tools include both traditional polishing wheels (scaifs) charged with diamond powder and oil, and more modern equipment, but the critical judgements — the angle of a facet, the sequence of operations, the decision to stop — remain in the hands of the cutter. Tolkowsky has been explicit that no machine can substitute for the trained eye and hand at the final stages of work on an exceptional stone.

Family Context and Legacy

Gabriel Tolkowsky is a cousin of Gabi Tolkowsky, another distinguished member of the family who has worked extensively in diamond cutting and design. The two are sometimes confused in trade literature, though their careers and specialisations are distinct. Gabriel's particular legacy is defined by his work on the two largest and most technically demanding diamonds cut in the modern era.

His position within the broader Tolkowsky narrative is significant. Marcel Tolkowsky's 1919 treatise established the theoretical framework for ideal diamond cutting; Gabriel's career demonstrates what that framework looks like when applied at the extreme limits of the craft. Together, they represent the intellectual and practical poles of a single tradition: the belief that diamond cutting is not merely a manufacturing process but a discipline in which science and artisanship are inseparable.

Tolkowsky's influence on the trade extends beyond his two most famous commissions. His documented methods and his willingness to discuss the optical principles underlying his decisions have contributed to a broader understanding, within the industry, of what light performance in a diamond actually means — and how it can be achieved or destroyed at the cutting wheel. In an era when automated cutting and grading have transformed the commercial end of the industry, his career stands as evidence that the highest level of the craft remains irreducibly human.

Recognition and Documentation

Tolkowsky's work has been documented in De Beers' own publications, in the trade press — including Rapaport Diamond Report and various issues of Gems & Gemology — and in broader histories of the diamond industry. The Centenary Diamond in particular has been the subject of substantial journalistic and industry coverage, and the cutting process was documented by De Beers with an unusual degree of transparency, given the stone's significance to the company's centenary celebrations.

He has been described by colleagues and clients as a cutter's cutter: a craftsman whose reputation rests entirely on the quality of his work rather than on self-promotion. In a trade not always characterised by modesty, this distinction is itself noteworthy.

Further Reading

• GIA Gems & Gemology — coverage of the Centenary Diamond
• GIA — History of Diamond Cutting