Over 90% of all sapphires are treated to enhance their colour. How do treatments affect the value of a sapphire? If the colour of the stone is supported by a lack of inclusions, good transparency, and even distribution of colour, as well as optimised by a well-executed cut, the value increases… and obviously, the bigger the better. The most valuable sapphires are those that possess a vivid blue hue and medium/medium-dark tone.Ī 100 carat sapphie from the Bemainty Mines in Madagascar.

Unlike the standardised grading of a diamond, where the value of the stone is determined by its colour, clarity, cut and carat (the money siding on the whiter, the cleaner, the bigger and most balanced) the grading of a coloured gem is 50% in its colour. Colour is considered in terms of hue (the spectral colour), tone (the lightness or darkness of the hue) and saturation (how vivid or intense the hue is). What factors determine the value of a coloured gemstone? A big blue sapphire is a very valuable gem indeed. These crystals are very rare and rarity adds value.

If the environment in which the crystal started growing in the earth remains stable, it has the potential to develop into a large, clean and vibrant gem. Read more: Discover the Storytelling Powers of Master Gem Carvers If it contains iron and titanium, it can appear blue - the sapphire. If it contains chromium, it can appear red. These impurities have the potential to change the crystal’s colour. So why does it command such prices when it is placed in jewellery? When the corundum crystal grows in the earth, it may let in chemical impurities. In fact, it is commonly used as an abrasive, think sandpaper or emery boards. Sapphire is a variety of the mineral corundum – a fairly abundant material composed of aluminium oxide. What makes Kashmir sapphires so special? What about the padparadscha? What role do treatments play in value? Here, Gem-A tutor, Beth West FGA DGA EG offers a beginner’s guide to sapphire value.

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