A superb Asscher cut diamond.  The large table facet and parallel lines make it much harder to hide inclusions.

Pippa Middleton has got engaged and her Asscher cut diamond engagement ring has had gossip columnists and jewellery watchers all abuzz (a side note from an expert: that 3 carat stone could not have cost 200k and if it did, the poor fiancé was ripped off). Inevitably, it has thrown this elegant cut of stone into the spotlight and we can expect the sales of Asscher cut diamonds to soar in the next few months, in the same way that sapphire and diamond engagement rings took off when her sister, the Duchess of Cambridge got engaged.

Pippa Middleton photographed sporting her new engagement ring.

Why are Asscher cuts so special?  A little history first... The cut was developed by Joseph Asscher in 1902 and it was the first diamond cut in the world to be patented worldwide- the Asschers held the patent until the middle of the 20th century.  Joseph Asscher himself was one of the most talented lapidaries of his day, his father having founded the diamond company that bears the family name and is still based in its original headquarters in Amsterdam.  As such, he was tasked with cutting and polishing the most famous diamond in the world, the Cullinan Diamond.  The 3106 carat (yes, that's four figures of carats) rough stone had been found in South Africa and gifted by the Transvaal Governement to Edward VII as a sign of their loyalty.  The cutting job was as nightmarish as it was prestigious.  Having none of the modern technology that avails us today, Joseph Asscher had to study the stone for months before making the first cut.  Diamonds maybe the hardest substance on earth, but if you cleave a stone at the wrong angle, there is a chance of shattering it.  He managed to cut right through a defective spot, splitting it between two stones and effecting the first cleave perfectly.  In recognition of services to the diamond industry, the Asscher Diamond Company was granted the prefix of Royal by Queen Juliana of the Netherlands, and the honor was renewed in 2011 by Queen Beatrix.

Archive photograph of Joseph Asscher making the first cut into the Cullinan diamond.

Asscher cuts are special stones because with square and rectangular stones, the color and clarity generally has to be higher than other cuts.  The large surface area of the table (the largest facet on top of a stone) and the clean parallel lines leave little room in which to hide inclusions.  With other cuts of diamonds, it is easier to cut them so that the inclusions are hidden by the crisscrossing of the other facets.  They were around before the modern emerald cut, which was only standsardised in 1940.  Both emerald and Asscher cut are step cut stones, meaning the facets on the crown of the stone form little steps rather than cross crosses, throwing the light out in a different way to other cuts.  A proper asscher cut is square; anything else is modified asscher cut or emerald cut.

For me, asschers are more timeless than emerald cuts, which are more overtly modern (although I wouldn't say no).  Even though the Asscher cut was invented well over a century ago, it has stood the test of time and never became gimmicky in the way that certain new cuts of diamond have.

The nine main cleavings from the Cullinan diamond before they were faceted into gems.