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Choosing a Gemstone:
What are the factors that make a gem rare and valuable? Much like a diamond, the various combinations of a stone's colour, clarity, cut and carat weight along with availability and accessibility determines rarity.
Colour:
Colour is typically the most important value-setting factor for gemstones. All gems have a preferred colour, or a relatively small range of preferred colours. The more the colour varies from this range – whether lighter or darker, more vivid or less – the less valuable the stone.
Colour is composed of three dimensions: hue, tone, and saturation.
• Hue refers to the impression colour usually noticed immediately, such as red, orange, yellow, green, blue and violet.
• Tone refers to the degree of lightness or darkness of an object, for example, a range of blue from light to dark, with numbers 0 – 10. 0 is so light as to be colourless (or white), and 10 is so dark it is black.
• Saturation defines the degree of purity of a hue. The terms “strength” and “intensity” also refer to this characteristic. The higher the proportion of pure colour, the higher the saturation. Colour saturation is divided into 6 levels. Level 1 is showing a strong undertone of grey (cool colours) or brown (warm colours) and is termed “Grayish” or “Brownish”. Level 6 is a pure “Vivid” saturation.
