One carat equals 1/5 of a gram in weight. For diamonds under a carat, each carat is divided into 100 points – similar to pennies in a dollar. 0.75ct. = 75 points, ½ ct. = 50 points
Every diamond is unique. Each reflects the story of its arduous journey from deep inside the earth to a cherished object of adornment. Yet all diamonds share certain features that allow us to compare and evaluate them. These features are called the 4Cs.
The Clarity Scale includes eleven clarity grades ranging from Flawless to I3. Given that diamonds form under tremendous heat and pressure, internal and external characteristics are common. These characteristics help gemmologists separate natural diamonds from synthetics and simulants, and identify individual stones. There are two types of clarity characteristics: inclusions and blemishes – the difference is based on their locations. Inclusions are enclosed within a diamond while blemishes are confined to its surface.
The Colour Scale extends from D (colourless) to Z (light yellow or brown). Although many people think of gem quality diamonds as colourless, most diamonds used in jewellery are nearly colourless with tints of yellow or brown. Colour grades are determined by comparing each diamond to a master set. Each letter grade represents a range of colour and is a measure of how noticeable the colour is.
The Cut Scale ranges from Excellent to Poor. A polished diamond’s beauty lies in its complex relationship with light: how light strikes the surface, how much enters the diamond, and how, and in what form light returns to your eye. The result is a display of three attributes. Brightness is the combination of all white light reflecting from the surface and interior of a diamond. Fire is the coloured flashes that can be seen in a diamond. Scintillation describes the sparkle of light you see in a diamond, and the overall pattern of bright and dark areas when you look at a diamond face-up. A polished diamond’s proportions affect its light performance, which in turn affects its beauty and overall appeal. Diamonds with good proportions optimize the interaction with light, and have good brilliance, fire, and scintillation. The Design (weight ratio, durability) and Craftsmanship (polish, symmetry) of a diamond also affect its cut quality, and are considered in determining a diamond’s Cut Grade.
Many diamonds emit a visible light when exposed to ultraviolet radiation. Although fluorescence is not a factor in determining colour or clarity grades, a description of its strength and colour is provided on Reports for identification purposes.