The Asscher cut is a square step cut with deeply cropped corners, developed by Joseph Isaac Asscher of the Royal Asscher Diamond Company in Amsterdam in 1902. Distinguished by its high crown, small table, and deep pavilion, the cut produces a mesmerising optical effect — concentric squares receding toward the centre — variously described as a windmill pattern or a hall of mirrors. It remains one of the most architecturally distinctive diamond cuts in the gemmological canon, closely associated with the Art Deco movement of the 1920s and 1930s and with a sustained revival in the early twenty-first century.

History and Origins

Joseph Asscher founded the I.J. Asscher Diamond Company in Amsterdam in 1854, and the firm rose to international prominence as cutters of exceptional skill. It was Joseph Asscher himself who, in 1902, patented the cut that bears his family name. The design was a deliberate refinement of the earlier emerald cut: where the emerald cut is rectangular, the Asscher is essentially square, and its proportions — particularly the high crown and the steep step facets — were calibrated to maximise the internal reflection characteristic of the design rather than to produce the scintillation of a brilliant cut.

The Asscher family's reputation was cemented in 1908 when Joseph Asscher was entrusted with cleaving the Cullinan Diamond, the largest gem-quality rough diamond ever found, weighing 3,106 carats in the rough. The firm retained its Royal designation — Royal Asscher Diamond Company — by appointment of the Dutch royal family.

The original patent lapsed, and by the mid-twentieth century the term "Asscher cut" had entered general use to describe any square step cut with cropped corners, regardless of manufacturer. The Asscher family subsequently developed the Royal Asscher cut, a proprietary variant with 74 facets (compared with 58 in the classic version) and a higher crown, re-patented in 2001 and cut exclusively by the Royal Asscher Diamond Company to this day.

Geometry and Optical Character

The classic Asscher cut carries 58 facets arranged in the step-cut manner: broad, flat facets running parallel to the girdle in tiers, rather than the triangular and kite-shaped facets of a brilliant cut. The outline is square with corner facets that produce an octagonal silhouette at the girdle. Typical length-to-width ratios fall between 1.00 and 1.05, preserving the square appearance.

The optical signature of the Asscher cut is fundamentally different from that of round brilliants. Because step facets act as large mirrors rather than as the small, dispersive facets of a brilliant, the cut produces broad flashes of light and dark rather than the rapid sparkle — scintillation — associated with round brilliants. The concentric-square reflection pattern visible through the table is the result of light bouncing between the parallel pavilion facets and the table, creating the characteristic hall of mirrors effect. This aesthetic is considered serene and geometric rather than fiery.

The Royal Asscher variant increases the number of facets on the crown and pavilion, introducing additional complexity to the reflection pattern and producing a somewhat brighter appearance than the classic cut while retaining the defining square geometry.

Quality Considerations: Colour and Clarity

The step-cut architecture of the Asscher presents particular demands on the quality of the rough from which it is fashioned. Because the large, open facets act as windows into the stone rather than as scintillating mirrors that mask inclusions, internal characteristics are far more visible to the naked eye than in brilliant cuts.

• Clarity: The trade consensus, supported by GIA grading practice, is that VS2 represents a practical minimum for eye-clean appearance in an Asscher cut of typical size. SI1 and SI2 grades that would appear clean in a round brilliant may show visible inclusions in an Asscher, particularly if those inclusions are positioned centrally beneath the table.
• Colour: The broad facets and relatively shallow table of the Asscher concentrate body colour, making it more perceptible than in a round brilliant of equivalent colour grade. Near-colourless grades — G or better on the GIA D-to-Z scale — are generally preferred for stones intended to appear white. Warmer tones in the H–J range may be acceptable in smaller stones or when set in yellow or rose gold, where the metal colour mitigates the contrast.

These quality sensitivities mean that Asscher-cut diamonds of high clarity and colour command a meaningful premium over their brilliant-cut counterparts of equivalent carat weight, reflecting both the stricter selection of rough and the greater loss of material during cutting.

The Art Deco Connection

The Asscher cut reached its first peak of popularity during the Art Deco period, roughly 1920 to 1940. The movement's aesthetic priorities — geometric precision, architectural symmetry, and restrained ornamentation — aligned naturally with the cut's square outline and rectilinear facet arrangement. Asscher-cut diamonds appear prominently in the canonical jewellery of this era: in platinum engagement rings with milgrain detail, in geometric brooches, and in the suites produced by the great Parisian and American jewellery houses of the period. The cut's association with Art Deco has remained durable; antique and estate Asscher-cut diamonds are frequently sought by collectors specifically for their period character.

Revival and Contemporary Market

After a period of relative obscurity during the second half of the twentieth century — when the round brilliant dominated the engagement-ring market — the Asscher cut experienced a well-documented revival from approximately 2000 onward. Several factors contributed: the centenary re-patenting of the Royal Asscher cut in 2001 attracted press attention; a broader consumer interest in vintage and Art Deco aesthetics drove demand for period-associated cuts; and the Asscher's distinctive appearance offered an alternative to buyers seeking individuality.

In the contemporary market, Asscher-cut diamonds are graded by the major laboratories — GIA, AGS, and others — using the same colour and clarity scales applied to all diamonds, though AGS has developed specific cut-quality criteria for step cuts. Laboratory-grown diamonds are now produced in Asscher cuts and occupy a growing segment of the market, particularly in the engagement-ring category.

The Royal Asscher cut remains a trademarked proprietary cut, and stones cut to that specification are accompanied by documentation from the Royal Asscher Diamond Company, including a laser-inscribed girdle identification number. Generic Asscher cuts — square step cuts with cropped corners produced by any cutter — are widely available and are simply described as "Asscher cut" in laboratory reports without implying any affiliation with the Amsterdam firm.

Setting and Wearability

The cropped corners of the Asscher cut serve a practical as well as aesthetic function: they reduce the vulnerability to chipping that would affect a fully square outline with sharp corners. The octagonal girdle profile distributes stress more evenly and makes the cut more forgiving in everyday wear than a princess cut, which retains its sharp corners. Prong settings are typically designed to protect the eight corners, with either four or eight prongs positioned at the corners and occasionally along the sides. Bezel settings complement the geometric outline effectively and provide additional protection to the girdle.

Further Reading

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