The Asscher cut is a square-format step cut distinguished by its deeply cropped corners, high crown, relatively small table facet, and deep pavilion. Invented in 1902 by Joseph Asscher of the I.J. Asscher Diamond Company in Amsterdam, it represents one of the few proprietary cutting styles in the history of the diamond trade to achieve genuine canonical status. In its classic form, the cut carries 58 facets arranged in concentric rectangular rows, producing the optical phenomenon commonly described as a hall of mirrors effect — a receding tunnel of reflected light that draws the eye deep into the stone rather than scattering brilliance across its surface. Because the cut prioritises this internal drama over the dispersive fire associated with brilliant cuts, it places extraordinary demands on clarity and colour, making it a natural vehicle for diamonds of the highest grades.

Origins and the Asscher Family

Joseph Asscher founded his Amsterdam cutting house in 1854; by the early twentieth century the firm had achieved international renown, most notably for cleaving the 3,106-carat Cullinan rough diamond in 1908 on behalf of the Transvaal government. The square step cut that bears the family name was patented in 1902 and represented a deliberate departure from the old mine and early round brilliant cuts then dominant in the trade. Its geometry — a near-perfect square outline with chamfered corners creating a subtle octagonal silhouette — suited the architectural sensibilities of the period and anticipated the aesthetic language that would fully flower two decades later in Art Deco design.

The patent lapsed after World War II, and the term "Asscher cut" entered general use to describe any square step cut with cropped corners, regardless of manufacturer. This means that stones described as Asscher cuts in the contemporary market vary considerably in their proportions and facet counts, and only those produced or licensed by the Asscher family carry the original specification.

Optical Character and Proportions

The characteristic optical behaviour of the Asscher cut arises from the interaction of its steep crown angles, compact table, and deep, step-faceted pavilion. Unlike brilliant-cut stones, which are engineered to return white light and spectral fire to the viewer in quantity, the Asscher cut creates a more contemplative visual experience. Light enters through the table, reflects between the parallel pavilion facets, and returns in a pattern of concentric squares or a cross-shaped windmill pattern — the precise appearance depending on the viewer's angle and the stone's individual proportions.

This geometry has several practical consequences for gem selection:

• Clarity visibility: The open, unbroken facet planes of a step cut act as windows into the stone. Inclusions that might be masked by the scintillation of a brilliant cut are plainly visible in an Asscher, making clarity grades of VS2 or higher strongly preferable for stones intended for prominent settings.
• Colour concentration: The deep pavilion and high crown concentrate body colour, meaning that colour grades which appear near-colourless in a round brilliant may read as distinctly tinted in an Asscher. Buyers typically seek D-to-H colour grades for white diamonds cut in this style.
• Length-to-width ratio: A true Asscher cut targets a ratio of 1.00 to 1.05, preserving the square outline. Ratios above approximately 1.10 begin to read as rectangular and are more properly described as emerald cuts.

The Royal Asscher Cut

In 2001, following a revival of interest in vintage cutting styles, the Asscher family introduced the Royal Asscher cut, a modernised proprietary variant developed by Edward and Joop Asscher. The Royal Asscher cut increases the facet count to 74 by subdividing the crown and pavilion facets, raising the crown height further and refining the culet. The result is measurably improved light return compared with the classic 58-facet version while preserving the signature hall of mirrors depth. The Royal Asscher cut is a registered trademark and is produced exclusively under licence, with each stone laser-inscribed with a unique identification number. It is assessed and certificated by major independent laboratories including the Gemological Institute of America (GIA) and the International Gemological Institute (IGI).

The Art Deco Connection

Although the Asscher cut predates the Art Deco period by roughly two decades, it became the emblematic diamond cut of that movement, which flourished from approximately 1920 to 1940. Art Deco jewellery drew on Cubist geometry, Egyptian revival motifs, and a machine-age admiration for precision and symmetry. The Asscher cut's octagonal outline, its rigorous linearity, and its cool, architectural internal reflections aligned perfectly with these values. Platinum settings of the period, with their milgrain borders, geometric filigree, and calibré-cut coloured stone accents, were designed around the cut's proportions. Surviving Art Deco pieces set with Asscher-cut diamonds — particularly those by Cartier, Van Cleef and Arpels, and Boucheron — command significant premiums at auction precisely because the stone and the setting exist in a designed relationship that cannot be replicated by substituting a modern brilliant.

Market Context and Contemporary Demand

The Asscher cut experienced a prolonged period of relative obscurity during the second half of the twentieth century, when the round brilliant cut dominated the diamond market and step cuts generally fell from fashion. Renewed interest emerged in the early 2000s, coinciding with the centenary of the original patent and a broader cultural appetite for vintage and Edwardian-to-Art-Deco aesthetics. The introduction of the Royal Asscher cut in 2001 provided a contemporary commercial vehicle for this revived interest.

In the current market, Asscher-cut diamonds occupy a distinct position. They are sought by buyers who prioritise the quality of a stone's crystal over its surface brilliance, and who favour the quieter, more introspective visual character of step cuts. Because the cut is unforgiving of inclusions and colour, well-proportioned Asscher-cut diamonds in high clarity and colour grades are relatively scarce in the secondary market, and original Art Deco examples with period-appropriate proportions — typically a higher crown and smaller table than many modern interpretations — attract particular collector interest.

The cut is applied predominantly to diamonds but appears occasionally in other transparent gemstones of high clarity, including aquamarine, morganite, and rock crystal, where its architectural character suits the cool, pastel tones of those materials. It is rarely applied to strongly coloured stones such as ruby or emerald, where the colour concentration effect of the deep pavilion can produce uneven saturation across the face of the stone.

Distinguishing Asscher from Emerald Cut

The Asscher cut is frequently described in trade contexts as a "square emerald cut," and the two share the same fundamental architecture of parallel step facets and cropped corners. The practical distinctions are principally of proportion: the emerald cut is rectangular, with a length-to-width ratio typically between 1.30 and 1.50, while the Asscher cut is square. The Asscher also traditionally features a higher crown and a deeper pavilion than most emerald cuts, which contributes to its more pronounced hall of mirrors effect. Both cuts are classified as step cuts and share the same demands on clarity and colour.

Further Reading

• GIA: Diamond Cut — gia.edu
• GIA Gems & Gemology: The Asscher Cut Diamond — gia.edu