The Asscher Cut Diamond: A Complete Guide

What is an asscher cut diamond?

An asscher cut diamond is a square step cut. Instead of the triangular and kite-shaped facets of a brilliant, it has long, flat facets arranged in rows, like the steps of a staircase, running parallel to the edges. It belongs to the same step-cut family as the emerald and the baguette.

Three things set it apart from a plain square carré cut. First, its corners are cut off deeply, so the outline is really an eight-sided square, close to the octagonal cuts. Second, it has a high crown (the top part above the girdle) and a small table (the flat facet on top). Third, it has a deep pavilion (the lower part), which pulls light inward and creates its signature pattern.

The Asscher is one of the 34 diamond cuts we work with, and it is one of the few named after a real family of cutters.

Where does the Asscher cut come from?

Joseph Asscher of the I.J. Asscher company in Amsterdam designed the cut in 1902 and patented it. The same firm was later trusted with splitting the Cullinan, the largest gem-quality rough diamond ever found, in 1908, which gives you a sense of its standing in the trade at the time.

The cut became a favourite of the Art Deco period in the 1920s and 1930s, when geometric lines and platinum settings were in fashion. That is why a vintage asscher cut diamond is usually found in a milgrain platinum ring with calibré-cut side stones. Older stones were cut by hand to suit the rough, so they tend to have even smaller tables, taller crowns and a larger culet (the tiny facet at the very bottom) than modern stones. They look softer and more moody, while modern Asschers are crisper and brighter.

Before step cuts and brilliants were common, many diamonds were rose cut, with a flat base and a domed top. If you are curious about older styles, see how older rose cuts compare with brilliants.

In the early 2000s the Asscher family released the Royal Asscher cut, a trademarked update with more facets. Today, most Asschers on the market are generic versions made after the original patent lapsed, cut by many different workshops.

How many facets does an asscher cut diamond have?

The traditional design is a 58 facet asscher cut diamond: the table, rows of steps on the crown, more rows of steps on the pavilion and a culet. The trademarked Royal Asscher has 74 facets. Modern generic Asschers vary, because each cutter adjusts the number of steps to save weight from the rough.

More facets is not automatically better. In any asscher diamond step cut, the beauty comes from broad flashes of light and dark, not sparkle. Extra steps make the pattern busier; fewer steps make it bolder. What matters most is that the steps are even and the corners line up.

That pattern is the heart of the asscher cut diamond design. Because the pavilion is deep, you see its steps reflected through the table as nested squares, with diagonal lines running from corner to corner. Gemmologists call it a windmill or ‘hall of mirrors’. It only appears cleanly when the stone is square and symmetrical; our guide to the Asscher windmill pattern shows good and poor examples.

What are the ideal proportions for an asscher cut diamond?

GIA does not give Asschers an overall cut grade, so you judge them on proportions, polish, symmetry and your own eyes. On a GIA report, an Asscher is usually described as a square emerald cut or a cut-cornered square step cut, so read the shape line carefully. The table below shows the ranges most experienced buyers look for.

The cut corners should be roughly equal in size. If one corner is noticeably larger, the octagon looks lopsided and the X in the windmill shifts off centre. How each diamond shape is judged explains why fancy shapes need this hands-on assessment.

What colour and clarity should you choose for an Asscher?

A step cut works like a window: the broad, flat facets show what is inside the stone. That makes clarity more important in an Asscher than in a brilliant of the same grade. Most people are happy from VS2 or better, and an SI1 can work only if you have checked it closely and the inclusions sit near the edge rather than under the table. Our Asscher clarity guide goes grade by grade.

Colour also shows more, especially in the corners and through the pavilion. In white gold or platinum, G or H colour is a sensible starting point; if you are sensitive to warmth, look at F or higher. In yellow or rose gold, H or I can look white because the metal warms everything around it. The same advice applies to the emerald cut, its longer cousin.

How big is a 1 carat asscher cut diamond?

Asschers carry a lot of weight in their high crown and deep pavilion, so they look smaller face-up than a round or princess cut of the same carat. A 1 carat round measures about 6.4 mm across; a 1 carat Asscher is usually about 5.5 mm square.

These are typical figures for a stone with about 65% depth. Two Asschers of the same weight can differ by 0.3 mm or more, so compare measurements, not just carats. The windmill pattern reads clearly from about 0.70 carat upward; smaller Asschers are often used as side stones or in earrings.

Asscher vs emerald, princess, cushion and radiant: what is the difference?

The emerald is essentially a stretched Asscher; our emerald vs Asscher comparison covers how the light differs. The princess shares the square outline but sparkles instead of flashing, and its sharp corners need protecting, as our princess vs Asscher guide explains. For softer edges, set the Asscher against the cushion; for the same cut-corner outline with more sparkle, look at the square radiant alternative.

Per carat, Asschers usually cost less than rounds of the same colour and clarity, because less rough is lost in cutting and demand is lower. They generally sit close to emerald cuts in price.

What is the best setting for an asscher cut engagement ring?

Because the corners are cut off, an Asscher is less likely to chip than a princess, but the corners are still where the setting does its work. Common choices:

• Four claws: one on each cut corner. Simple, shows the most diamond and keeps the square outline clean.
• Double or V-claws: two claws or a V on each corner for extra security and a bolder look.
• Bezel: a rim of metal around the edge. Very secure, modern, and it suits the Asscher's geometry.
• Halo: a square or octagonal halo makes the stone look larger, which helps offset its small face-up size.
• Art Deco three-stone: the Asscher flanked by step-cut side stones, usually in platinum with milgrain detail.

For side stones, baguette side stones and tapered trapezoids continue the step-cut look without competing with the windmill. Our page on settings that suit an Asscher has side-by-side examples, and wedding bands that sit flush beside an Asscher covers matching bands.

Natural or lab-grown asscher cut diamonds: how much do they cost?

Asschers are cut from both natural and laboratory-grown diamond, and the two look the same to the eye. Lab-grown diamond has the same crystal structure, hardness (10 on the Mohs scale) and refractive index (2.42) as natural diamond; it is simply grown in a laboratory rather than mined. Lab-grown Asschers cost much less and are easy to find in larger sizes. Natural Asschers are rarer, particularly well-cut ones above 2 carats.

As an approximate guide, a natural 1 carat Asscher in G–H colour and VS clarity sits around AUD 6,000–12,000, while a lab-grown 1 carat Asscher of similar grades is often around AUD 700–2,000. Prices move with the market, so treat these as ranges, not quotes. Both should come with an independent grading report from a lab such as GIA or IGI.

How to choose an asscher cut diamond: step by step

1. Read the report. Check the shape description (often square emerald or cut-cornered square step cut), measurements, colour, clarity, polish and symmetry.
2. Work out the ratio. Divide length by width; aim for 1.00–1.05 so it reads as a true square.
3. Check table and depth. Look for roughly 60–68% on both, and a girdle that is not extremely thin or thick.
4. Watch a 360° video. Look for a crisp, centred windmill with an X running cleanly to each corner.
5. Hunt for inclusions. Step cuts show them, so check under the table and as the facets flash.
6. Check colour in the corners. Warmth gathers there first, especially in white metal.
7. Plan the setting. Decide on claws, bezel or halo before you commit, and confirm the corners will be covered.

If any term on the report is unfamiliar, our jewellery glossary explains it in plain English.