Pure beryl is colourless, often called white, and although quite rare, tends not to be valuable because it does not have much brilliance. Colours, as in many gemstones, are caused by small amounts of impurity, usually metallic oxides. This is a another case where impurity is desirable. Chromium, in the form of chromic oxide, causes the bright grassy green colouring in beryl, thereby producing emeralds. Vanadium can also affect the exact shade, as may traces of iron. It is also possible to have green beryl which is not emerald, because the colouring agent is not chromium.

In general, when judging an emerald’s value, color is of paramount importance: the more vivid (deeper?) the green the more valuable the stone. Of course, there are attractive lighter green emeralds that are lively and vivid when set in jewelry, as well as darker green emeralds that make up for there lack of brightness in the richness of the color.  Generally speaking, however, very light or dark emeralds are less valuable.  And, as far as clarity is concerned, unlike diamonds a finely colored emerald is not significantly devalued by inclusions

Emerald green is the colour of life and of eternally returning spring. For centuries, however, it has also been the colour of beauty and of eternal love. Even in ancient Rome green was the colour dedicated to Venus, goddess of love and beauty. Today there are still many cultures and religions where green holds a special position. For example, green is the holy colour of Islam. All states of the Arabian league sport green banners symbolising the unity of their religion. But also within the Catholic church green holds an important status, as among the liturgy colours green is considered the most natural and elementary one.

Splendid Emerald green is a colour communicating harmony, love of nature and a primeval joy of life. You cannot ever get too much of this unique colour, as Pliny already pointed out "Green is pleasant to the eye without tiring it.”. Green is characterised as fresh and full of life, never as monotonous. And as this colour keeps on changing gradually between bright daylight and artificial lamplight, Emerald green in all its hues and shades will preserve its vivid energy.