The diamond, a symbol of eternity and purity, has fascinated humanity for millennia.

From its etymological origins to its evaluation criteria, and its appearances in historical jewellery, let's delve into the sparkling universe of this precious stone.

Origin of the term "carat"

The word "carat" finds its roots in the ancient Greek "kerátion", meaning "carob seed". These seeds, known for their uniform weight, were used in Antiquity as units of measure for precious stones. This practice continued through the ages, with the term evolving through the Arabic "qīrāṭ" and Italian "carato" to become "carat" in French. Today, the carat is a unit of mass equivalent to 0.2 grams, standardised in 1907 to unify commercial transactions.

Although carob seeds are no longer used to weigh diamonds, their historical role remains crucial in modern terminology.

The 4Cs of diamonds

To assess a diamond's quality and value, experts rely on four fundamental criteria known as the "4Cs":

Carat (weight), Colour, Clarity, and Cut.

1. Carat (Weight) The carat measures the diamond's weight. One carat equals 0.2 grams. While weight influences the apparent size of the stone, two diamonds of the same weight can have different values based on the other criteria.

2. Colour A diamond's colour is evaluated on a scale from D (colourless) to Z (yellow or brown tint). Colourless diamonds are the rarest and thus the most valuable. However, diamonds with intense hues, such as blue or pink, known as "fancy colour diamonds", are also highly sought after.

Fancy Colour Diamonds: Rarity and Mystery

While colourless diamonds are most sought after for their purity and brilliance, fancy colour diamonds possess an equally fascinating beauty and exceptional rarity. These stones, called "fancy diamonds", are distinguished by vibrant hues due to chemical elements or anomalies in their crystal structure.

Main diamond colours and their origins

🔹 Blue – The presence of boron in the diamond's structure absorbs certain wavelengths of light, giving the stone a bluish hue. The renowned "Hope Diamond" is one of the most emblematic examples.

🟡 Yellow and orange – These colours are due to traces of nitrogen, which alter how the diamond absorbs light. The "Tiffany Diamond", one of the largest known yellow diamonds, is an iconic example.

🟢 Green – This rare hue is caused by natural radiation exposure over millions of years underground. Unlike other colours, green is often limited to the diamond's surface.

🔴 Red and pink – Extremely rare, these colours result from plastic deformation of the diamond's crystal structure during its formation. The "Moussaieff Red Diamond", weighing 5.11 carats, is one of the most famous in the world.

🟣 Violet – Likely caused by a combination of hydrogen traces and structural alterations, this type of diamond is exceedingly rare.

🟤 Brown and champagne – These shades are also due to a distortion in the crystal structure and are more common than other coloured diamonds.

⚫ Black – Unlike other coloured diamonds, black diamonds owe their colour not to chemical impurities but to numerous inclusions of graphite or pyrite, which absorb rather than refract light.

The rarity and value of fancy diamonds

Fancy colour diamonds are extremely rare, representing less than 0.1% of diamonds extracted. Their value depends on the intensity of their hue, classified on a scale from Faint to Fancy Vivid. The more saturated and uniform the colour, the more valuable the diamond. Today, these fascinating diamonds are prized not only for their brilliance but also for their unique character. They are often set in exceptional jewellery and sought after by collectors and fine jewellery enthusiasts.

3. Clarity Clarity is determined by the presence or absence of internal inclusions and surface blemishes.

The clarity scale includes:

• FL (Flawless): No inclusions or blemishes visible under 10x magnification.
• IF (Internally Flawless): No internal inclusions, but slight surface blemishes.
• VVS1 and VVS2 (Very Very Slightly Included): Inclusions very difficult to detect under 10x magnification.
• VS1 and VS2 (Very Slightly Included): Inclusions hard to see under 10x magnification.
• SI1 and SI2 (Slightly Included): Inclusions easy to see under 10x magnification.
• I1, I2, and I3 (Included): Inclusions visible to the naked eye, potentially affecting brilliance.

4. Cut Cut refers to how a diamond is shaped and polished. An optimal cut maximises light reflection, imparting a diamond’s characteristic sparkle. Proportions, symmetry, and polish are crucial in evaluating the cut.

Different Diamond Cuts: Brilliance and Precision

The diamond's cut is a key factor influencing its brilliance and value. A well-executed cut maximises light reflection, whereas a poorly done cut can diminish its sparkle. Each shape has a specific number of facets that determine how light is captured and reflected. The main diamond cuts and their characteristics

💎 Round Brilliant Cut – 57 or 58 facets This is the most popular shape, optimised for maximum sparkle. Its perfect symmetry and unrivalled play of light make it the preferred choice for engagement rings and classic jewellery.

💎 Princess Cut – 58 facets Square and contemporary, it combines modernity and brilliance. Its step-cut and vibrant sparkle make it a compelling alternative to the brilliant cut.

💎 Emerald Cut – 50 to 58 facets Rectangular with step facets, it highlights the transparency and purity of the diamond rather than its sparkle. Very elegant, it is prized for its sophisticated look.

💎 Oval Cut – 56 to 58 facets Sleek and refined, it gives the illusion of a larger diamond due to its extended surface. Its elongated shape enhances the hand and visually lengthens the fingers.

💎 Pear Cut (or Teardrop) – 58 facets A subtle blend of the oval and brilliant cuts, the pear shape imparts a unique elegance to the diamond, perfect for pendants and earrings.

💎 Marquise Cut – 58 facets Inspired by a smile, this elongated and tapered cut was commissioned by Louis XV to evoke the lips of the Marquise de Pompadour. It gives an impressive volume effect and dazzling brilliance.

💎 Heart Cut – 57 or 58 facets A symbol of love, this delicate and complex cut requires great precision to ensure perfect symmetry and evenly distributed light.

💎 Asscher Cut – 58 facets Similar to the emerald cut but square, it is distinguished by a "hall of mirrors" effect, showcasing the depth and purity of the diamond.

💎 Cushion Cut – 58 to 64 facets Square or rectangular with softened corners, it offers a warm, vintage sparkle, highly prized in high jewellery. Each cut influences the diamond's brilliance and personality. Some prioritise brilliance, others highlight clarity and unique form. The choice depends on the desired style and effect on the jewellery.

Historical diamond jewellery

Over the centuries, numerous diamond-adorned pieces have marked history:

• The Koh-i-Noor: This legendary 105.6-carat diamond, originating from India, now adorns the British crown.
• The Hope Diamond: A blue 45.52-carat diamond, famous for its unique hue and the legends of curses surrounding it.
• The Regent: Discovered in India, this 140.64-carat diamond is displayed at the Louvre and once belonged to Louis XIV.

These jewels testify to humanity's enduring fascination with diamonds and their central role in art and culture.

In conclusion, the diamond is far more than just a precious stone. Its history, unique characteristics, and symbolism make it an unparalleled gem, celebrated throughout the ages for its beauty and rarity.

The anecdote of the waterlogged carat and its influence on the diamond market

Before the standardisation of the metric carat in 1907, diamond weight was determined by the seed carat, based on carob seeds, believed to have uniform weight.

However, a surprising practice sometimes skewed these weights: waterlogged carats. Unscrupulous traders soaked carob seeds in water before weighing diamonds, slightly increasing their weight and, consequently, their value. During the humid seasons, too, it was more profitable to sell diamonds than to buy them. This subtle yet effective manipulation influenced early precious stone transactions until the 0.2-gram carat was officially adopted in the early 20th century to ensure a reliable and universal unit of measurement.

This anecdote illustrates the historical importance of precise weight in valuing diamonds and why standardisation was essential for establishing trust and transparency on the jewellery market.