They are usually “oiled” at the mines – a process that uses oil to fill the cracks and inclusion spaces in a technique practised for centuries.Īquamarine is another variety of beryl, and owes its delicate blue-green palette to ferrous iron. To help improve their clarity and colour, emeralds are treated in several ways. The inclusions also make emeralds a more brittle gemstone, often confused with it being soft. However, emeralds can be sourced from many parts of the world, including Russia (the Urals have produced emeralds for more than 100 years), Zambia, Brazil, Zimbabwe, Afghanistan and Ethiopia some emeralds from these mines will rival the best Colombian emeralds.Įmerald typically have many inclusions the French say they have a jardin (garden) inside them. When the colour of beryl is too light to be called emerald, it is termed ‘green beryl’.Ĭolombia remains the major source of emeralds, retaining the best reputation and usually commanding a price premium. The price drops when accompanied by a bluish tinge, and continues to devalue further when coloured a yellowish tinge from iron impurities. Like sapphire, the vibrant colour of emerald – a form of beryl – has been adored from ancient times.Ĭreated by trace impurities of chromium and vanadium, the intense green colour is the most prized. Sapphires are often heat-treated to remove silk inclusions, thus enhancing clarity and richness of colour. Green sapphires also owe their colour to iron. These impurities absorb specific parts of the light spectrum, and the remaining light reflected to the eye gives colour to the gemstone.īlue is caused by traces of titanium and iron the more iron present, the darker the stone.

Sapphire is corundum an allochromatic mineral that derives colour from chemical impurities in the crystal structure. However, paler versions are still in high demand and the teal hue – a mix of blue and green – has also soared in popularity in recent years, with premium specimens sourced from Australia, Nigeria, and Montana in the US. Rich blue Ceylonese gemstones are the most well- known and valuable variety of sapphire, and the standard against which other blue gems are measured. Jeweller discovers the chemical and structural causes of colour in captivating natural blue and green gemstones, from Ceylon sapphires to imperial jade.

Bright blue gemstone