Asscher cut
A square step-cut diamond with deeply cropped corners and a hypnotic windmill pattern of concentric reflections. Geometric, architectural, and uncompromising on clarity.
The Asscher cut is a square variant of the step cut, patented by Joseph Asscher in Amsterdam in 1902. Its defining feature is the deep corner crops — far more pronounced than an emerald cut or square emerald — which give it a near-octagonal face-up outline and produce the signature "windmill" or cross-shaped optical pattern seen when looking into the stone.
Like all step cuts, the Asscher uses long parallel rectangular facets rather than the triangular kite facets of a brilliant. The result is a calm, architectural beauty: instead of scintillating sparkle, you see deep reflections and a mesmerising geometric symmetry. The large open table leaves inclusions fully exposed — VS1 is the practical clarity floor, and many buyers choose VVS2 or better.
The Asscher became the defining diamond cut of the Art Deco era in the 1920s. It was modernised in 2001 when the Asscher family introduced the Royal Asscher: 74 facets instead of 58, adding brilliance while retaining the octagonal character.
- STYLE
- Step cut
- IDEAL L:W
- 1.00–1.05
- CLARITY
- VS1+ recommended
- ORIGIN
- Amsterdam, 1902
Classic Asscher
The original Asscher cut patented by Joseph Asscher. 58 facets, deeply cropped corners giving a near-octagonal outline. The windmill pattern — a cross of reflections — is its signature. Demands very high clarity; inclusions hide nowhere.
L:W 1.00–1.05. 58 facets. Deeply cropped corners. Steps: 3 on crown, 3 on pavilion. Clarity: VS1+ strongly recommended.
Royal Asscher
An updated 74-facet version developed by the Asscher family in 2001. Additional facets on the crown and pavilion produce more brilliance and sparkle than the classic cut, while retaining the octagonal outline and step-cut character.
L:W 1.00–1.05. 74 facets. Slightly higher crown. More brilliance than classic. Still needs VS2+ clarity.
Square emerald
A generic square step cut without the Asscher brand designation. Shallower corner crops than the true Asscher give it a more rectangular outline. Sometimes labelled "square emerald" by laboratories. Slightly less dramatic windmill effect.
L:W 1.00–1.15. Shallower corner crop than true Asscher. Step lines more like a compact emerald cut. GIA grades as "square emerald cut".
Asscher vs Emerald cut
Two step cuts with the same facet philosophy — but fundamentally different shapes and optical characters.
Square with deep crops
- Square outline, deeply cropped corners (near-octagon)
- Windmill / cross optical pattern from centre
- L:W 1.00–1.05; compact, jewel-like face-up
- Step facets more visible — less forgiving on clarity
- VS1+ recommended; VVS2+ for 2 ct+
- Art Deco icon; 1902 Amsterdam heritage
Rectangular with shallow crops
- Rectangular outline, shallow corner crops
- Hall-of-mirrors: elongated parallel reflections
- L:W 1.40–1.55; elongating, finger-lengthening
- Large open table; inclusions easy to see
- VS1 recommended; VS2 acceptable at smaller sizes
- Also Art Deco roots; named for emerald gemstone cuts
Classic vs Royal Asscher
The same square octagonal outline — one century apart in design.
Classic Asscher
- Facets
- 58
- Crown facets
- 25 (including table)
- Pavilion facets
- 33
- Step rows (crown)
- 3
- Corner crop
- Deep (near-octagon)
- Trademark
- None (design is public domain)
The original windmill pattern in its purest form. Fewer facets mean a starker, more graphic optical effect. Most unforgiving on clarity.
Royal Asscher
- Facets
- 74
- Crown facets
- 33 (including table)
- Pavilion facets
- 41
- Step rows (crown)
- 4
- Corner crop
- Deep (same octagonal outline)
- Trademark
- Registered · laser-inscribed ID
Extra facets add sparkle without losing the step-cut character. Slightly more forgiving on clarity; still requires VS2+ for clean appearance.
Clarity & colour guide
Step cuts punish inclusions and colour more than any brilliant cut. Plan accordingly.
Clarity
The Asscher's open table is one of the least forgiving surfaces in diamond cutting. Use this as a floor, not a target.
| GRADE | VERDICT | NOTE |
|---|---|---|
| FL / IF | Best | Flawless to naked eye and loupe. Ideal for exceptional stones. |
| VVS1 / VVS2 | Excellent | Inclusions invisible to naked eye; eye-clean. Recommended for 2 ct+. |
| VS1 | Recommended | Practical sweet spot. Eye-clean in most Asschers. Strong starting point. |
| VS2 | Acceptable | Eye-clean in smaller stones. Evaluate video carefully for 1.5 ct+. |
| SI1 | Risky | Often visibly included in a step cut. Only if positioned carefully. |
| SI2 / I | Avoid | Inclusions very likely visible. Not recommended for Asscher cut. |
Colour
Step facets show body colour more easily than brilliant facets. Asscher buyers typically go one grade higher than they would for a round.
No visible warmth. Spectacular in Asscher's deep table. Premium price.
Effectively colourless face-up. Most popular choice for Asscher.
Slight warmth in large stones. Excellent value; set in white gold/platinum.
Warmth visible in step cuts above 1 ct. Better suited to yellow/rose gold.
Noticeable warmth in Asscher. Only for yellow gold settings or budget builds.
Visible yellow in step cuts. Not recommended unless warmth is intentional.
Proportions
The Asscher cut has no GIA cut grade — proportion evaluation is the buyer's responsibility.
| PARAMETER | AVOID | ACCEPTABLE | IDEAL |
|---|---|---|---|
| Length-to-width | > 1.10 | 1.06–1.10 | 1.00–1.05 |
| Depth % | < 58% or > 73% | 58–60% or 70–73% | 61–68% |
| Table % | < 55% or > 70% | 55–57% or 68–70% | 58–67% |
| Girdle | Very thin or very thick | Thin–thick | Very thin–slightly thick |
| Clarity | SI1 or below | VS2 (small stones only) | VS1 or better |
History
Asscher Diamond Company founded
Joseph Isaac Asscher establishes the I.J. Asscher Diamond Company in Amsterdam. The firm becomes one of the world's leading diamond cutters.
Asscher cut patented
Joseph Asscher patents the square step cut with deeply cropped corners. The design is immediately distinguished by its octagonal outline and concentric square reflections.
The Cullinan commission
The Asscher family is entrusted with cleaving the Cullinan diamond — then the world's largest rough diamond at 3,106 carats — for the British Crown Jewels. Joseph Asscher reportedly fainted after making the first cut.
Art Deco golden age
The Asscher cut becomes the defining diamond shape of the Art Deco era. Its geometric lines and architectural character perfectly match the movement's aesthetic. Hollywood and aristocracy alike adopt it.
Royal Asscher introduced
Exactly one century after the original patent, the Asscher family introduces the Royal Asscher cut — 74 facets, a higher crown, and laser-inscribed identification. The update adds brilliance while honouring the original design.
Vintage revival
Growing interest in Art Deco aesthetics and "antique" cuts drives renewed demand. The Asscher cut becomes one of the fastest-growing non-round shapes as buyers seek alternatives to the round brilliant.
Frequently asked questions
What makes an Asscher cut different from an emerald cut?
Both are step cuts, but they differ in shape and optical character. The Asscher cut is square (L:W 1.00–1.05) with very deeply cropped corners that give it a near-octagonal face-up outline. Its signature is the windmill or cross-shaped optical pattern — concentric square reflections radiating from the centre. The emerald cut is rectangular (L:W 1.40–1.55 typically) with shallower crops and a hall-of-mirrors effect of elongated rectangular flashes. The Asscher's deep crop and square proportion produce a more hypnotic, centred optical pattern.
What clarity grade do I need for an Asscher cut?
The Asscher cut's large table and step facets act as windows into the diamond, making inclusions more visible than in any brilliant cut. VS1 is the practical minimum for most buyers; many choose VVS2 or better for stones above 1.50 ct. Unlike a round brilliant, there is no scintillation to mask flaws — an SI1 that would be eye-clean in a round is often visibly included in an Asscher. The classic Asscher with fewer facets is the most unforgiving; the Royal Asscher's additional facets provide slightly more coverage.
What is the Royal Asscher cut?
The Royal Asscher is a modernised version developed by the Asscher family (I.J. Asscher Diamond Co.) in 2001, one century after the original patent. It increases the facet count from 58 to 74 by adding extra facets on the crown and pavilion. The result is more brilliance and fire than the classic cut, while retaining the octagonal outline and step-cut aesthetic. The Royal Asscher is a trademarked design; stones are registered and come with a laser-inscribed ID. Generic "Asscher cuts" without the trademark are often marketed as "square emerald cuts" on GIA reports.
Does an Asscher cut look smaller than a round of the same carat weight?
Yes, noticeably. The Asscher's deep pavilion and square shape mean it carries more weight below the girdle than a round brilliant of the same carat. A 1.00 ct round measures about 6.4–6.5 mm in diameter; a 1.00 ct Asscher is typically about 5.5–5.7 mm across. The deeply cropped corners further reduce the visual face-up area. Buyers who prioritise face-up size often move to a cushion or oval, though the Asscher's depth is precisely what creates its optical depth and windmill pattern.
What colour grade should I choose for an Asscher cut?
Step cuts show colour more readily than brilliant cuts — the large open facets allow you to see the body colour of the stone rather than having it broken up by scintillation. Most buyers choose H or better for an Asscher; G is a common target for a face-up colourless appearance. D–F stones look spectacular in the Asscher's deep table. I and below can look noticeably warm in a larger stone. If setting in yellow or rose gold, the mount colour reduces the concern; for platinum or white gold, H+ is a reasonable guide.
When was the Asscher cut invented?
The Asscher cut was patented in 1902 by Joseph Asscher of the I.J. Asscher Diamond Company in Amsterdam. It became closely associated with the Art Deco movement of the 1920s, which favoured geometric shapes, architectural lines, and understated elegance. The original patent expired, making the design freely available, but the Asscher family retained the "Royal Asscher" trademark for their updated 74-facet version introduced in 2001.