Carat

This term refers to the weight of a gemstone. One carat = 0.20g.

The term carat is often abbreviated to ‘ct’. Each carat is divided into 100 ‘points’, therefore a ¾ carat stone can be referred to as ‘75 points’.

All other things being equal, diamond prices increase with weight.
This is because larger diamonds are more rare than smaller ones.

Where did the term ‘carat’ come from?
The term carat derives from the word ‘carob’. Early gem traders would use carob beans to balance the scales, as counterweights against gemstones.

What does the term ‘magic size’ mean?
Certain carat weights are called ‘magic sizes’ – 0.50cts, 0.75cts, 1.00ct, 1.50ct, 2.00ct and so on. It is at these weights that the prices jump up significantly due to customer demand. However, when looking at a stone there is virtually no difference visually between 1.49cts and 1.50cts.

Cut

The cut of a gemstone can refer to its shape, and also its proportions.

We often think of a diamond’s cut as shape (round, emerald, pear), but a diamond’s cut grade is also about how well a diamond’s facets interact with light. The cut is crucial to a stone’s final beauty and value.

A diamond is evaluated on how successfully it interacts with light to create desirable visual effects such as:

Brightness: Internal and external white light reflected from a diamond

Fire: The scattering of white light into all the colors of the rainbow

Scintillation: The amount of sparkle a diamond produces, and the pattern of light and dark areas caused by reflections within the diamond

Grading will also take into account the design and craftsmanship of the diamond, including its weight relative to its diameter, its girdle thickness (which affects its durability), the symmetry of its facet arrangement, and the quality of polish on those facets.

 

Shape

There are many different diamond shapes. The most popular are round brilliant, princess, pear, emerald, oval, marquise, heart and asscher.

all-cuts

 

Asscher Cut: Introduced in 1902 by renowned diamond cutter Joseph Asscher, this diamond shape utilises many of the same cutting techniques as the emerald cut. What sets asscher diamonds apart are their uniquely angled and cropped corners creating a timeless look.

Cushion Cut: First introduced to the jewellery market in the early 1800s, the cushion cut diamond is rich with diamond history, though today’s cushion cut is slightly different. Cut into a square or rectangular shape with rounded corners and sides, it’s considered by many to be a more vintage version of the round cut diamond.

Emerald Cut: Emerald cut diamonds are usually rectangular in shape. Distinguished by bevelled corners and step facets, this type of diamond is more transparent than other shapes, often requiring higher standards of clarity.

Heart Cut: Living up to its name, the heart cut diamond has become synonymous with love and affection, making it an excellent choice for an anniversary or engagement ring. One of the most demanding diamond cuts to create, a heart shaped stone requires great skill and dexterity from the diamond cutter.

Marquise Cut: The marquise cut is rumoured to have been specially developed for King Louis XIV of France who wanted a diamond that simulated the smile of Marquise de Pompadour. The elongated marquise stone has gracefully pointed ends for a dramatically beautiful appeal.

Oval Cut: Cut with the same number of facets as a round diamond, an oval shape emits nearly the same level of brilliance and fire. Due to its elongated shape, the oval cut can appear larger than a round diamond of equal carat (weight).

Pear Cut: Exuding elegance, the pear shape diamond (also referred to as a drop cut or teardrop diamond) is cut to resemble a drop of water with a single point and rounded end. The result is a cross between a round and marquise cut.

Radiant Cut: Relatively new to the jewellery industry, radiant diamonds were introduced a little more than 20 years ago. This unique shape is a stunning hybrid of a traditional round cut and an elegant emerald cut, resulting in a square, near-square, or rectangular orientation. As the name suggests, radiant diamonds tend to emit a beautiful, memorable glow.

Round Brilliant Cut: In the early 1900s, diamond cutters began to experiment with new techniques. A breakthrough came in 1919 with the introduction of the round brilliant cut. Due to its ability to maximize fire and brilliance, the round brilliant cut has become the standard and most popular way to cut diamonds. Like the old European cut, a round brilliant cut diamond has a circular girdle and 58 facets. However, the round brilliant cut lacks a culet. The round brilliant cut became prevalent during the Art Deco and Retro periods.

Princess Cut: A square stone with 90-degree corners, the princess shape originated in the United States in 1980. The most desirable princess diamonds are perfectly square in shape, with the more rectangular variations decreasing in value.

Step Cut: Cutting style with mainly square and rectangular facets arranged in concentric rows, simulating a mirrored staircase.

 

Antique Stone Cuts

As specialists in antique jewellery we recognise the beauty and extraordinary quality of antique cut diamonds and original antique pieces. Many of these stones would have been passed down from generation to generation in families, sometimes being re-set by the bride in current styles.

Every antique stone is unique, special and one of a kind. The stones themselves were cut by hand using a series of tools including a cleaver. It often took months to study diamonds before cutting, and then months to cut, to ensure the most beautiful result. The famous Cullinan diamond took two years to study and cut.

 

The Different Antique Cuts

Rose Cut: The rose cut features a flat bottom with a dome-shaped crown, rising to a single apex. With anywhere from 3 to 24 facets, a rose cut diamond resembles the shape of a rose bud. The rose cut dates to the 1500s and remained common during the Georgian and Victorian eras.

Old European: 1700s–1900. These stones are largely round in shape, have circular girdles, small tables, a heavy (or tall) crown and great overall depth.

Old Mine: 1830s–1900. These have more of a square or cushion shape in comparison to the Old European. It was an early version of the modern brilliant cut. They have a high crown, small table and large ‘open’ culet. The old mine cut was originally developed to sparkle its best in incandescent or candle light; the perfect evening accessory.

Old Cut: Refers to a stone cut with a rounded outline and large culet, predominantly prior to 1910. This style was meant to maximise light return in low light conditions, namely candlelight.

Antique Cushion: 1830s–1900. This is often referred to as a ‘pillow’ shape. It has a large or ‘open’ culet and is rectangular to square, with rounded corners. Like the modern emerald cut, your eyes will delve deep into an antique cushion cut stone.

Transitional Cut: 1870s–1940s. This is the transition between the old European and the modern brilliant cuts. The angles of these stones are more similar to the modern brilliant to other antique cuts. For example, the table facet size is increased, and culets are nearly nonexistent or ‘somewhat large’ but could not be described as ‘large’ or ‘open’.

 

Clarity

The term 'clarity' refers to the purity of the diamond.

The term ‘clarity’ refers to the purity of the diamond. Natural diamonds are the result of carbon that has been exposed to extreme heat and pressure within the earth’s core. This process can result in a variety of tiny natural imperfections within or on the surface (blemishes) of the stone. The grading scale came about when previously general terms such as ‘eye clean’ were used, which could be misinterpreted.

Such imperfections can be smaller diamond or spinel crystals growing within the larger stone or little surface bruises or sections of the ‘skin’ of the uncut diamond left on the surface of the cut stone.

Most inclusions do not affect the structure, life or beauty of gem quality diamonds and are usually not visible to the naked eye.

The diamond clarity scale has six categories, which are divided for a total of 11 specific grades:

Clarity

Flawless (F): No inclusions and no blemishes are visible to a skilled grader under 10x magnification. These stones are exceptionally rare.

Internally Flawless (IF): No inclusions and only blemishes are visible to a skilled grader under 10x magnification.

Very, Very Slightly Included (VVS1 and VVS2): Minute inclusions that range from extremely difficult to very difficult to see by a skilled grader under 10x magnification.

 Very Slightly Included (VS1 and VS2): Minor inclusions that range from difficult to somewhat easy to see by a skilled grader under 10x magnification.

Slightly Included (SI1 and SI2): Noticeable inclusions that are relatively easy to see by a skilled grader under 10x magnification.

Included (I1, I2 and I3): Obvious inclusions that are visible to a skilled grader under 10x magnification.

Colour

The diamond colour grading scale ranges from D to Z.

A chemically pure and structurally perfect diamond has no hue. Trace elements such as Nitrogen and Boron in diamond can cause the stone to have small yellow or blue hues. Other impurities can make a diamond look slightly grey or brown. Most colour distinctions are not visible to the untrained eye, but can make big differences in the prices of the diamonds.

Previous to this system, jewellers used a variety of different ratings such as A, B and C and 0-3. The D-Z scale started afresh, with D colour being completely colourless, down to Z which has noticeable colour.

Naturally coloured diamonds that fall outside the normal colour range are called fancy diamonds. They are either yellow or brown diamonds that have more colour than a Z grade, or are a colour other than yellow or brown.