Emerald: untreated from the Habachtal and from Torrington

Emerald is the best-known gemstone of the beryl family — and at the same time the one you have to look at most closely. Because almost every emerald offered in the trade is treated. Untreated stones are the exception, and those are exactly what we work with in our workshop.

A beryl coloured green by chromium and vanadium

Beryl is a beryllium aluminium silicate and colourless in itself. Trace elements make the familiar varieties out of it: iron gives aquamarine, manganese gives red beryl — and chromium or vanadium gives the green of emerald. Depending on the deposit the colour ranges from a strong, saturated green to light, fresh tones with a slight blue cast.

Emerald almost never grows undisturbed. The crystals are shot through with fine fissures, inclusions and growth veils; jewellers have always called this the „jardin“, the garden of the emerald. Eye-clean stones are extremely rare.

Why almost every emerald is treated

Because fissures reach through to the surface, they can be filled. Traditionally colourless oil is used, today synthetic resins as well. The filling makes the fissures optically less visible and the stone clearer — but it is not permanent. Oil can dry out or be washed out during cleaning, resins can yellow. The stone then suddenly looks different from how it did at purchase.

An untreated emerald, by contrast, always shows exactly what nature laid down. What you see stays that way. That is precisely why „untreated“ is no side issue with emerald, but the most important characteristic after colour.

Habachtal: emerald from the Hohe Tauern

The Habachtal in the Salzburg Pinzgau is the best-known emerald occurrence in central Europe. The emeralds sit there in dark mica schist, grown into a narrow zone between different rocks where beryllium and chromium met. The Habachtal has been searched and mined for centuries; today only individual collectors find material there.

Habachtal emeralds stay small, are almost always heavily included and rarely yield cuttable pieces. A faceted, untreated stone from the Habachtal is therefore above all one thing: a piece of Alpine mineralogy that you otherwise see almost only in museum cases.

Torrington: emerald from New South Wales

In the New England highlands of New South Wales, around Torrington, lies one of the areas where emerald has been found in Australia. The region is known for its tin and topaz occurrences; the emerald comes from the same granite-related rocks.

Torrington emeralds are typically light — a fresh, delicate green, often with a hint of blue. They are usually clearer than Alpine emeralds, but remain distinctly included as well. Anyone expecting emerald in a strong, dark green will find something else here: a light, luminous colour that looks especially calm in a step cut.

What to look for when buying

• Treatment: the most important question. A reputable seller can answer it clearly — oiled, resin-filled or untreated.
• Colour: it determines the price more than anything else. With light stones, evenness matters more than saturation.
• Inclusions: they belong to emerald. A large, flawless stone at a conspicuously low price is a warning sign.
• Synthetics: synthetic emerald from flux or hydrothermal growth has been on the market for decades and is often hard to recognise without a laboratory.
• Confusion: green beryl, tsavorite, chrome diopside or green tourmaline look similar at first glance.
• Origin: with emerald it can often be narrowed down gemmologically and noticeably affects value.

Hardness and wearability

With a Mohs hardness of 7.5 to 8, emerald is hard enough for jewellery. The many internal fissures make it sensitive to knocks and pressure, though. Ultrasonic and steam cleaning are out of the question, and setting it takes experience. For a ring worn every day we prefer a protected setting; for pendants and earrings emerald is unproblematic.

How we cut emerald

The classic emerald cut — a step cut with clipped corners — is not named after this stone by chance. Broad, calm facets show the colour as a surface, the clipped corners protect the brittle material, and the rough piece can be used with as little loss as possible. We therefore work mostly with step cuts in rectangular, carré and octagon shapes and follow, where the rough demands it, its natural form — which is how trapeze, hexagon and marquise shapes come about too.

Our cut stones can be found under Emerald. On the red relative from the same mineral family, read our piece on red beryl from Utah. And if you have rough material of your own that should be cut, you will find everything further under Services.