Emerald

Emerald is beryl, the same mineral as aquamarine and morganite, coloured green by traces of chromium, vanadium and iron. Few gems have been loved for longer, and the story begins in Africa: the first known emerald mines were in Egypt, worked in antiquity.

Today Africa is again at the heart of the emerald trade. Zambia is the world's second-largest producer, and its emeralds are known for a cool, slightly bluish green.

Where the name comes from

The word comes through Old French esmeraude and Latin smaragdus from the Greek smaragdos, simply "green gem".

Beliefs and legends

• Cleopatra's passion. The first known emerald mines were in Egypt, and Cleopatra loved the stone and wore it in her royal adornments.
• A glimpse of the future. An emerald placed under the tongue was believed to let its owner see the future, and wearing one was said to reveal whether a lover's promise was true.
• Solomon's gift. Legend says emerald was one of four precious stones God gave King Solomon, giving him power over all creation.

The colours

• Bluish green to pure green: the most desirable, vivid and not too dark.
• Cool and bluish: typical of Zambian emeralds; Colombian stones are often warmer. The two overlap, and colour alone does not prove origin.
• Too light or too yellow: then the stone is green beryl, not emerald, and worth much less.

Treatments, honestly

Almost every emerald carries tiny fractures, and more than nine in ten are filled with oil or resin to make them less visible. This is accepted in the trade and must always be disclosed. Laboratories grade the level of filling as minor, moderate or significant, and an untreated emerald of the same quality is worth much more. We tell you what we know about each stone, including its treatment level, before you buy it.

How to judge an emerald

• Colour comes first: a vivid bluish green to pure green, evenly spread, and transparent.
• Expect inclusions. The trade calls the mossy pattern inside an emerald its jardin, its garden. An emerald clean to the eye is rare and especially valuable.
• Ask about the filling. Ask for the treatment level in writing.
• The cut protects it. The step-cut "emerald cut" protects the corners of this brittle gem and gives the claws a safer seat.

Caring for your emerald

Emerald is 7.5 to 8 on the Mohs scale, but its fractures make it more fragile than ruby or sapphire. Wear it with care and avoid knocks. Clean it only in warm soapy water with a soft brush. Never use an ultrasonic cleaner or steam: vibration can weaken fractures, and heat can draw the filling out. Strong light and chemicals can also affect the filling.

At a glance

Mineral	Beryl (beryllium aluminium silicate), green variety
Hardness	7.5 – 8 Mohs; brittle, often fractured
Colours	Bluish green to green
From	Zambia (Kafubu), Zimbabwe (Sandawana), Ethiopia, Madagascar; also Colombia, Brazil
Treatments	Most are oiled or resin-filled. Level disclosed per stone
Care	Warm soapy water only. No ultrasonic, no steam