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Beryl Gemstone Information

Beryl is from the Greek word 'Beryllos' meaning 'the blue-green colour of the sea'. It is a species of mineral that includes the well known varieties emerald and aquamarine. The lesser known varieties of beryl also produce attractive gemstones, they are becoming more widely known through internet exposure. The term 'precious beryl' applies to all gem-quality beryl varieties, except emerald and aquamarine. The example above is a golden beryl.

Varieties of beryl:

Emerald: Highly saturated green beryl. Grass green coloured with good clarity are rare and very highly priced.

Aquamarine: Typically light blue to sea green in colour, deeper blue colours are prized.

Yellow Beryl: A yellow variety of beryl ranging from a light lemon yellow to a rich golden yellow, the latter is named golden beryl.

Heliodor: A yellow-green coloured beryl. In the gem market heliodor is often used to describe golden beryl.

Morganite: A pink to peach coloured variety of beryl.

Green Beryl: Light green beryl is classified as green beryl in the gem market, only the richly saturated stones are classified as emerald. Although light green beryl is not considered to be emerald, very light blue beryl is still classified as aquamarine.

Bixbite: Also called red beryl or scarlet beryl, is a red variety discovered in the Wah Wah Mountains of Utah in the United States of America. The only other deposit is found in New Mexico. It is coloured by manganese and rarely found in large gem grade crystals. It is very seldom cut as gemstones and normally sold to collectors, as crystals in matrix.

Goshenite: A colourless variety of beryl from Goshen, Massachusetts in the United States of America. All other varieties of beryl are essentially goshenite with impurities that are responsible for the colour. For example, iron impurities are responsible for the colour in aquamarine and chromium impurities (sometimes vanadium) produce the grass green colour of emerald.

Maxixe: Pronounced mah-she-she, is a sapphire-coloured blue variety of beryl, separate from aquamarine. The mineral is named after the mine in Minas Gerais Brazil where deposits were found. The blue colour is caused by radiation and is unstable in both natural and treated stones; although faded stones can be restored by further radiation treatment.

Maxixe occurs naturally, but other varieties of beryl (yellow, pink or green) can be irradiated to create the medium to deep blue colour of the natural stone.

Physical Properties

Stone type:
Variety of the species Beryl.
Crystal System:
Hexagonal.
Chemical Composition:
Beryllium aluminium silicate - Be3Al2(SiO3)6.
Colour:
As described above for each variety.
Lustre:
Vitreous.
Pleochroism:
Dichroic: distinct.
Dispersion:
Low.
Hardness:
7 1/2 - 8 on the Mohs' scale of hardness.
Toughness:
Fair for most varieties. Poor to good for emerald, heavily included stones are susceptable to damage.
Cleavage:
Very imperfect.
Density in gm/cc:
2.65 to 2.80
Double refraction:
Yes.
Refractive index:
1.56 to 1.60

Common Treatments

Pale morganite may be heat-treated to deepen the colour.

Goshenite may be irradiated to produce pink coloured stones.

Pale yellow material may be irradiated to improve the colour saturation.

Emerald may be oiled to fill cracks and improve the colour.

Aquamarine is heat-treated to remove yellow and green tints. Some green beryl is heat-treated to create blue coloured stones.

Maxixe may have been irradiated to deepen the blue colour. The colour is restored to faded stones by the same treatment.

Yellow, pink and green beryl may be irradiated to create the blue colours of natural maxixe.


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