A Brief History of Diamond Cuts
The art of diamond cutting involves fashioning natural diamond stones into faceted gems. Cutting diamonds involves specialist knowledge, skill and of course, specialist equipment. It is almost impossible to say with certainty when and where the skills of the diamond polisher originated, although it is thought that they would have been located in India in the 11th century.
By the early part of the 14th century the art of diamond faceting had reached Europe via Venice. The limited supply of diamonds that arrived in Europe came from India, and it is suggested that the Indians considered these stones as inferior in terms of their qualities.
Here is a brief history of cut diamonds throughout the ages:
The Point Cut
The first known form of polished diamond was referred to as the point cut. The point cut diamond comprises a polished or cleaved octahedron. As the octahedral faces themselves could not be polished, the angles of the faces were polished at a slight inclination to the planes.
The Point Cut
The point cut represented the only recorded faceting for flat polishing of diamond up until the 14th century.
The Table Cut
The 14th century saw the appearance of the table cut. This was an adaptation of the point cut where one of the points was ground away to produce a table. A culet was often ground opposite this table. This developed into the full table cut.
The table cut (single cut)
The table cut (full cut)
The table cut remained popular up until the 17th century and many point cut diamonds were re-cut into this style.
The Rose Cut
The rose cut was probably first introduced in the early 15th century. The cut employs a faceted dome with a flat base. The effect can be quite pleasing and weight loss is small. One of the main disadvantages of the rose cut is its tendency to lack fire in comparison to cuts that were developed later and were improved in terms of brilliance and fire. The adamantine lustre is very prominent, however, as it is not masked by fire or brilliance. Rose cuts were often set in closed-back settings and they remained popular for a number of years.
There are many famous diamonds in the rose cut style, including the Great Mogul. Larger stones were often designed as double rose cuts and briolette cuts. Famous diamonds cut as a double rose include the Sancy. However, the double rose is more commonly used in other gem materials and is rarely seen in smaller diamonds.
Three facet rose
Six facet rose
Rose cuts are no longer a common choice of cutting style, but are still cut to order and are very common in old jewellery.
The Single and Double Cut
In the early 17th century the table cut was modified and developed into the single cut. This was achieved by grinding away the edges of the octahedron. This development progressed further to create the double cut.
A rounded version of the single cut, with angles similar to those found in the modern round brilliant cut is still used today for small loose diamonds goods. This is also called the eight cut.
The old single cut
Modern single cut
The double cut exists in several forms and is sometimes called the ‘Mazarin cut’, in honour of the 17th century French statesman and collector of diamonds, Cardinal Mazarin.
The Triple Cut – Brilliant Cut
The triple cut was the first brilliant cut diamond stone. The triple cut is believed to have been developed in the mid-17th century. It comprises 58 facets including the table and culet, and was often cushion-shaped in outline with a deep crown and pavilion. It is often referred to as the ‘old mine cut’.
Old mine cut
Old European Cut
The introduction of diamond bruiting machines in the 19th century made it possible for diamond polishers to achieve truly round cut diamonds. Like the triple cut, the old European cut consists of 58 facets including the table and culet. It has a small table and a large culet with a deep crown and pavilion.
Old European cut
At this time diamond was still a rare material and it was essential to retain as much weight as possible from the original stone. It was only after the discovery of diamonds in South Africa in the late 19th century that polishers began to experiment with angles and proportions.
The Modern Round Brilliant Cut
Credit for the modern round brilliant cut is often attributed to an American named Henry Morse. Henry Morse opened the first diamond cutting factory in the USA in 1860 and spent many years experimenting with the angles and proportions of the round brilliant cut. These experiments saw the cut change shape from thick and dumpy to the more slender proportions of today.
Modern round brilliant cut
Diamond Cut History - Some Notable Dates:
1919 - Nineteen year old Marcel Tolkowsky produced a thesis which included design specifications for the American standard also known as the American ideal cut. His work became the basis for the modern round brilliant.
1940 - Eppler produced the European cut.
1970 - The International Diamond Council (IDC) produced a set of ideal ranges.
Variations of the brilliant cut:
In all cuts, variations from ideal proportions may be dictated by the nature of the rough. For example, to get the biggest cut stone from an oddly-shaped crystal (or if the rough is very dark, or very pale colour) it will be cut shallower or deeper than the ideal proportions to retain as much weight as possible. Often the presence of obtrusive inclusions determines the cut of the stone.
There are many variations on the brilliant cut which include variations on outlines. Variations include the
following shapes/ cuts:
Pear (also known as drop)
Marquise (navette or boat-shaped)
Modified square or rectangular cut (also known as the princess cut, this is a trade name and not the style of cut)
Cushion (antique cut – square shaped with rounded corners)
The term ‘fancy shape’ is generally used to describe all shapes that are other than round.
Other styles of cut include the emerald and step cuts. Baguettes and tapered baguettes are modifications of the step cut and are used for small stones.
Square Cut - Carre
Step cuts do not produce as much fire and brilliance as brilliant cuts and inclusions or colour tints are often far more obvious. Larger emerald cut diamonds should be of good quality and symmetry.
Most new cuts are variations on traditional ones. However, almost every year there is a new variation or adaptation of an old style. For example, in 1988 De Beers launched five new diamond cuts designed to produce higher yield from rough with obvious draw of colour. These were called the flower cuts and included the fire rose, flower, marigold, zinnia and dahlia.
These cuts are still created today, but despite all the variations and adaptations the brilliant cut still remains the most popular diamond cut.
Quality of Cut
The quality of a diamond cut is categorized according to the following characteristics:
Proportions of a diamond
The proportion of a cut refers to the relationship between the sizes and angles of various facets. This is sometimes termed the ‘measurements’ of stones.
Symmetry of a diamond
The symmetry of a diamond cut refers to the symmetrical appearance of the stones. For example, the concentric positions of the table and culet in a round stone.
Polish of a diamond
The polish refers to the quality of the polished stone.
Ideal Proportions for Diamonds
To achieve the brilliant cut design facets are angled to achieve the best combination of brilliance and fire. The angle between pavilion facets and the girdle is important, as it controls the production of brilliance by reflecting rays of light from the back facets. This angle, therefore, must be correct to produce maximum internal reflection. For diamonds, the pavilion angle is close to 41° for this to be achieved. Although called the ‘ideal cut’, the proportions vary between various cuts.
Brilliance of a diamond
Brilliance refers to the degree of brightness resulting from reflection of light by a gemstone when viewed through the crown facets. It is made up of light reflected from the pavilion facets and from the surface of the crown facets.
Fire of a diamond
Fire refers to the breaking up of white light into spectral colours when white light passes through the inclined facets of a cut material. Diamond, strontium titanate and synthetic moissanite are noted for their great amount of fire.
Pavilion of a diamond
If the pavilion of a stone is either too deep or too shallow, light leaks out of the back facets reducing the brilliance.
Effect of Pavilion angle/depth on light
In diamonds with shallow pavilions an effect called a ‘fish eye’ may be seen. This is where a reflection of the girdle can be seen through the table of the stone.
If the pavilion is too deep the effect of a dark circle may be visible, either taking up a large proportion of the table or the entire table (see diagram). This is sometimes called a ‘nail head’.
It was soon realized that there could be a degree of tolerance applied to proportions and angles which would not necessarily diminish the whole effect. This resulted in the ranges given by the IDC in 1970. Since this time fashions have changed and some slight alterations have occurred in the standard modern round brilliant. Below is a summary of the range of proportions we see in diamonds today.
The effect of light in diamonds
Let us consider the properties of diamonds:
Diamond has a high refractive Index (RI) of 2.419
The RI of a diamond determines the reflectivity. The lower the critical angle, the higher the reflectivity will be
Light striking the interface between an optically denser and rarer medium at an angle greater than the critical angle is totally internally reflected (TIR)
Reflectivity is the amount of light being reflected from the surface of the stone. Diamond has a high reflectivity of 17% perpendicular to the surface
Hardness of a diamond
The harder a material is, the greater the polish and the sharper the facet edges of the stones.
Lustre of a diamond
The amount of light reflected from the surface of material is dependent on the reflectivity and polish of the surface. As diamond has high reflectivity and hardness it has a very good lustre. The lustre of diamond is referred to as being adamantine.
Dispersion of a diamond
As light passes through two inclined faces, i.e. the crown facets, it is split into its component colours. This effect is called ‘fire’. Diamond has a dispersion of 0.044.
The round brilliant cut is designed to bring all these factors together and balance them in such a way as to maximize the impact of the diamond. It is the most popular and sought after diamond cut.