Asscher cut

An Asscher is a square diamond whose facets run in long, flat steps from the girdle toward the centre, like the rungs of a stair. GIA describes step-cut facets, a high crown and a small table, which together create the "hall of mirrors" effect. Many show a distinct X pattern when seen face-up. The corners are cut, and on vintage stones with large bevels the outline can look octagonal.

It is often called a square emerald cut, and the two do look related. An Asscher offers a better balance of scintillation than a similar emerald cut while still looking quieter than a modern brilliant such as the round brilliant. As with every shape except the round, GIA does not give it an overall cut grade.

Joseph Asscher created the cut in 1902 and it was popularized in the Art Deco era. The International Gem Society says it was patented, calls it the first patented diamond cut, and says the patent was extended until the Second World War.

Joseph Asscher also cut the Cullinan, found in 1905. Cullinan I, a pear-shaped stone of 530.20 carats, sits in the British royal sceptre, and Cullinan II, a cushion of 317.4 carats, in the imperial state crown. Both came from a rough diamond of about 3,100 carats.

The original has 58 facets in three rows on the crown and three on the pavilion. The Royal Asscher adds 16 facets for a total of 74. By GIA's account, Edward Asscher, Joseph's grandson, redesigned the cut after attending GIA's 1999 International Gemological Symposium, adding two rows of eight facets to the bottom and narrowing existing rows. The International Gem Society gives no exact year, saying only that the revision came nearly a century after the original.

On GIA's account, the Royal Asscher has an international patent, the Royal Asscher Company limits the range of angles used to cut it, and it is the only company allowed to cut a Royal Asscher stone. A stone sold simply as an "Asscher cut" is a square step cut and may not be a Royal Asscher.

They do. GIA's guidance is that clarity and colour are especially important in an Asscher, because these diamonds tend to show inclusions and body colour more readily than brilliant cuts. The large, open facets act like a window. Look at clarity and colour in the stone itself, under good light, and compare it with a radiant cut, which is more forgiving. For an Asscher, GIA recommends clarity of VS2 or better and colour of G or better, particularly above 2 to 3 carats.

For symmetry, GIA's guide points to sharp symmetry in well-cut examples, which often show the X pattern. Check that the square is even and that the corners are cut evenly. For larger stones, its guide adds that double prongs are often used to secure the bevelled corners of stones of 3 carats and above. See the prong setting entry for how corners are held.

It suits a buyer who likes Art Deco geometry and a calm, mirrored effect more than a burst of sparkle, and who is willing to buy a cleaner, whiter stone because the cut reveals so much. It is a poor fit if you want the cut to hide flaws or if maximum sparkle is the goal.

The diamond shapes guide compares it with the square princess cut and the others. You can see finished rings in the engagement ring collection, or use the design studio to set out an Asscher with the setting you prefer. Diamond Bros designs custom engagement rings by appointment, and the showrooms page lists where to go.