Diamonds Explained: The Antique & Vintage Buyer’s Guide

The most common types of antique diamonds which you will find on the market today are Old European cuts, Old Mine cuts, Briolettes, and Rose cuts. Old Asscher cuts are available, but they are rare. When looking at antique diamonds, they are assessed using the same cut, colour, clarity and carat weight (the four Cs) criteria as a modern diamond. However, there are some fundamental differences which need to be factored in. Firstly, an old cut diamond in its original setting is worth more than the sum of its parts, as it contains its history, styling and provenance. The next difference to be factored in is symmetry. Since old cuts were cut by hand as opposed to using modern equipment, they have enormous differences in symmetry. The proportions of an old cut diamond will also be very different to those of a modern cut. An old cut will prioritise the weight retention of the rough stone. There will also be different faceting patterns and typically higher crowns and deeper pavilions on an old cut, which will reflect the light differently to a modern cut. The limited supply of antique diamonds also needs to be factored into the assessment, with some old cuts being rarer than others.
Here at Carus Jewellery, we take all of these factors into account when we are evaluating antique diamonds.

The Four Cs of Diamond Quality

The four Cs of diamond quality is a grading system established by the Gemological Institute of America (GIA) to evaluate and compare the quality of any diamond. This grading system is the global standard used to evaluate both antique and modern cut diamonds. The GIA started developing the system in the 1940s and codified it in 1953. Before this, jewellers and retailers used various confusing and often poetic terms to describe the quality of a given stone. For example, a clear and colourless stone could be referred to as “good water” or a “river”. The GIA produced its very first diamond grading report in 1955, establishing the four Cs (cut, colour, clarity, and carat) as we know today.

Cut

A diamond’s cut is the most crucial “C” in the four Cs because it directly affects the stone’s sparkle, fire and brilliance. Diamond cut refers to the proportions and reflective quality of a diamond. It does not refer to the shape of a diamond. When a diamond is cut too shallow, the light entering from the table is reflected back out through the bottom of the pavilion. Whereas when a diamond is cut too deep the light entering through the table is reflected out through the side of the pavilion. In both of these cases, the diamond will appear dull. In the case of a well-cut diamond, the light entering through the table is reflected off each of the pavilion’s facets with most of this light leaving through the crown. Resulting in a bright and lively diamond, known as a diamond’s fire and brilliance. Diamond cut is graded on a scale of excellent, very good, good, fair and poor.
Buying tip: If a diamond has an excellent cut, all the light is reflected back out through the top of the stone. This intense fire and brilliance overpowers any slight yellowish tints or tiny inclusions. So that they cannot be seen with the naked eye. If a buyer prioritises the cut, they can slightly compromise on colour and clarity to get a larger carat weight for less money.
In the case of antique diamonds, the carat weight was prioritised over the cut. Keeping the pavilion deep and the table small, allowed the gem cutter to maximise the weight from the rough stone and minimise waste. Historically, there were also technological limitations to how a diamond could be cut. Old cuts have open culets at the bottom simply because the technology did not exist to cut these to a point without the risk of chipping the stone. If you look directly down through an old cut diamond from the top, you will be able to see a small dark circle; this is the open culet.
Modern cuts are optimised for brilliance, which is bright, white light returned through the top of the stone. This is achieved with a lower crown and a wider table.
Old cuts are optimised for fire, which is the separation of light into rainbow flashes. This was achieved with a higher crown and narrower table, which acts like a prism. When these old cuts are viewed under candlelight, a beautiful, slow-moving rainbow of flashes can be seen.

Colour

Diamonds not only form in white but also include yellow, pink, blue, brown, orange, red, purple, grey and black. These coloured diamonds are known as fancy diamonds and are graded on separate colour scales. White diamonds are graded on a scale of D to Z, with D being colourless and Z being light yellow. Diamonds are graded by gemologists in a lab where the lighting is controlled and using a set of master diamonds as shown in the above photo. To the naked eye, no difference can be seen from grade D to grade J, under normal lighting and without a set of master diamonds. However, the price difference between these two grades would typically be double. It is from grade K onwards that the colour differences can be seen under normal lighting conditions.
Once a diamond has been set in a ring or piece of jewellery, it becomes much harder to see the colour if there is any present. This is partly due to the position of the diamond, which will be viewed from the table when mounted in a setting. As opposed to being viewed from the pavilion, as gemologists do when colour grading a diamond. When viewed from the table the fire and brilliance of a diamond is at its height. Also, a yellow gold setting will make any yellow present in a diamond less obvious. Whereas a white metal setting will highlight any yellow colour in a diamond. So in general, colour grades D to J are considered suitable for a platinum or white gold setting. While colour grades K to Z would be more suitable for a yellow gold setting. As such, an antique old mine cut diamond with a colour grade of K looks warm and rich in a yellow gold setting and would also look historically accurate.
Just as with clarity, a diamond’s colour becomes more important as the carat size increases, typically above 1ct. As it becomes easier to see any colour present in a larger diamond.

Clarity

Diamonds are formed deep within the Earth’s crust, under huge pressure. As a result, virtually all diamonds will contain some level of imperfection. It is extremely rare for a diamond to be classed as flawless or even internally flawless. It is estimated that only one in every five thousand diamonds graded are classed as flawless. It has also been estimated that around a third of all diamonds sold have a clarity grading of SI1 or SI2. This grade of inclusion cannot normally be seen by the naked eye. So to give an idea ( as each diamond is unique ) of the difference between a SI1 clarity grade and a VS1 clarity grade. A VS1 clarity grade diamond would typically be about twice the cost of a SI1 diamond. Of course, this would be subject to the colour, cut and carat of each diamond being identical. As a general rule, clarity becomes more important for diamonds over 1ct in size, as it is easier to see any imperfections in a larger diamond.
When it comes to clarity, how light interacts with antique diamonds is very different to how light interacts with a modern diamond. Old mine cuts have larger, blocky facets as opposed to the smaller, sharper and slender facets of a modern cut. These blocky facets are incredibly forgiving of internal inclusions. They make a slightly included stone (SI1 or SI2) look completely clear to the naked eye. An old cut causes the light to bounce around internally multiple times before exiting. This concentration of fire makes it very difficult for the naked eye to see inclusions. On the other hand, antique rose cuts behave the exact opposite and will clearly show any inclusions. Rose cuts have no pavilion, and as such, have a completely flat base. Light that enters does not bounce around inside and so no chaotic fiery light reflects. Rose cuts also have wide triangular facets on their dome-shaped crown. This makes every inclusion inside immediately visible. For this reason, clarity is a top priority when choosing an antique rose cut diamond.

Carat

A diamond carat is the measurement of a diamond`s weight. As opposed to the actual size of the diamond, which is commonly believed. A 1 carat diamond is 200 milligrams. This standardisation of diamond weight was first introduced in America in 1913 and thereafter was accepted worldwide. Diamonds weighing less than 1 carat are measured in points. Since there is 100 points in a single carat, a diamond weighing 50 points would be half a carat. The vast majority of diamonds sold, weigh 1 carat or less.
It should be noted that old cuts prioritised the retention of weight from the rough stone. This was done by having deeper pavilions and higher crowns. So a one carat old European cut will look smaller when viewed from the top down than a one carat modern cut.

Historical Diamond Cuts

Rose Cut (1500s – 1800s)

The rose cut is one of the oldest diamond cuts and is still one of the most romantic cuts. The cut originated in India during the late 15th century and was perfected by European gem cutters in the 16th century. The design of this cut features a flat base (no pavilion) and a low-profile faceted dome, rising to a single point. The faceted dome can contain anything from three to twenty-four triangular facets. These wide triangular facets were perfectly suited to catch candlelight and return slow-moving romantic flashes of light. This effect could be heighted by foil-backing the stone in a closed back setting, which was a popular technique used in Georgian Jewellery. This cut declined in the early 1900s due to the development of the round brilliant cut, which maximised brilliance, particularly under electric light.
In recent years, the rose cut has seen a resurgence in its popularity in contemporary design. This is due to its low-profile, which makes it ideal for everyday wear, particularly in rings. Also since all of the carat weight is concentrated within the dome, a one carat, a rose cut diamond looks up to 40% bigger than a standard brilliant cut diamond.

Old Single Cut (1600s – present)

A single cut diamond is a very old, simplified cutting style, which features a flat table top with eight facets on the crown and eight facets on the pavilion. This single cut evolved from the primitive “table cut” in the mid 1600s. The original cuts were often octagonal in shape as opposed to round and were often times “boxy” in shape. With the invention of the mechanised bruting machine in the late 1800s, gem cutters could easily facet tiny diamonds, as small as 0.05ct. These tiny diamonds were referred to as “melee” diamonds and used as accent diamonds. The single cut peaked around the 1920s to the 1950s. By the 1950s, the single cut was no longer used as the centre piece stone but rather as an accent stone. By the 1970s, gem cutters in Antwerp had introduced the 32 facet cut to bring more sparkle to tiny diamonds. Then by the 1980s, precision equipment allowed the cutting of a full 57 facets on a tiny diamond, as small as 0.6mm.
Today, the single cut is still used, but normally only for high-end watches, where a quieter, mirror-like reflection on the watch face is preferred.

Old Mine Cut (1700s – 1800s)

Old mine cut diamonds got their name in the late 19th century to distinguish them from the newer and rounder diamonds from South Africa. The old mine cut was the forerunner to the modern round brilliant cut diamond. It featured 58 facets and was characterised by a squarish cushion shape, a high crown with a small table and a deep pavilion with a large culet. The old mine cut was the dominant diamond cut of both Georgian Jewellery and Victorian Jewellery. The old mine cut was designed to prioritise fire over brilliance and so these diamonds produced slow-moving, dramatic flashes of colour when viewed under candlelight. By the 1890s, the old mine cut was starting to transition into the old European cut and by 1900, it had faded out of use.
Here at Carus Jewellery, it has always been my personal opinion that the old mine cut is the most romantic of all the diamond cuts, particularly for engagement rings.

Old European Cut (1890s – 1930s)

The old European cut evolved directly from the old mine cut and while the old mine cut was squarish in shape, the old European cut was perfectly round. The invention of the mechanised diamond-bruting machine in 1874 allowed the old European cut to be the first perfectly round cut to be produced. This cut was the dominant diamond cut during the late Victorian Era, Edwardian Era, and the Art Deco Era. During this time, people were moving away from candlelight to electric light and the old European cut was designed for this. It had sweeping triangular facets on its pavilion, which produced rainbow-coloured flashes of light when viewed under warm indoor lighting such as the early incandescent bulbs or gas lights. By the late 1930s, the old European cut was being phased out in favour of the transitional cut, which would go on to evolve into the modern round brilliant cut.

Old Asscher Cut (1902 – 1930s)

The old Asscher cut was the world’s first diamond cut to be patented in 1902. Joseph Asscher designed this new geometric shape, which was a square step cut diamond with a high crown, deep pavilion, small table and featured dramatically cropped corners. This cut created a striking “hall of mirrors” optical effect. The popularity of the old Asscher cut skyrocketed during the Art Deco Period, where it became the dominant diamond cut for that era. It perfectly matched the architectural trend of the era, with its sharp angles, parallel lines and symmetrical concentric squares. The cut declined in use during the Great Depression and during WWII, the Asscher family was greatly impacted by the Nazi occupation of the Netherlands. In 2001, the Asscher family revived the cut and added an extra row of facets to the bottom, which updated the cut to perform better under modern electric lighting. However, lovers of Antique and Vintage Jewellery still highly prize the original old Asscher cut for its moody and deep contrasts.

Antique Cushion Cut (early 1900s – present)

The antique cushion cut evolved at the same time that the old mine cut transitioned to the old European cut. Gem cutters took the old mine cut’s squarish shape and added more refined and precise facets to it and so created the antique cushion cut. The cut had deeply curved corners, a high crown and a thick, bulky pavilion. It had an open culet at its base and if you look directly down into the stone from the top (table), you will see a small dark circle, which was intentional. The cut also featured large, distinct facets. The Hope Diamond is a famous example of an antique cushion cut diamond.
The antique cushion cut never really stopped being used, but rather it evolved over the years into the modern cushion brilliant that we see today.

For further information about diamonds, please see: Diamond formation, history, meaning and folklore.

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Recommended Citation (MLA) Format:

Hoyne, John. “Diamonds Explained: The Antique & Vintage Buyer’s Guide.” Carus Jewellery, n.d., https://carusjewellery.com/diamonds-explained/.

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