Value and Cutting

The high esteem in which choice emeralds are held and the high cost of this gem are due in great part to the rarity with which a gem approximating perfection occurs. Most of the grass-green beryl crystals are cloudy and dull; these disqualifications are due to fissures and cracks, but also to infinitesimally small enclosures of foreign matter, either fluid or solid, such as scales of mica. When clouded by fissures emeralds are called by jewellers "mossy."

A "perfect" (approximately of course) emerald-beryl stone is worth nearly, sometimes fully, as much as a fine natural ruby and more than a diamond—that is, a stone of one carat or thereabouts,—while large stones are so rare that they bring fancy prices out of all proportion to their size. The average emerald beryl fit for cutting is but a small stone. Tradition and unscientific accounts tell of phenomenally large emeralds, but one of the largest and finest actually known to exist belongs to the Duke of Devonshire; this is a natural crystal, measuring two inches across the basal plane, and weighs 8 9/10 ounces, or 1350 carats; in colour, transparency, and structure it is almost without a fault. This fine stone was found in the emerald mines at Muzo in Colombia, South America. Another large crystal known belongs to the Czar of Russia; its measurements are reported to be twenty-five centimetres (nearly ten inches) in length and twelve centimetres in diameter.

The character of each piece of the rough beryl placed in the hands of the lapidary decides what cut shall be applied to an emerald. Small stones are usually cut as brilliants or rosettes, while the large ones are sometimes cut as a simple table stone, or more generally step-cut with brilliant facets on the upper portion. Cut gems of good colour and transparency are mounted in an open setting; paler stones were formerly, in Europe, reinforced with a green foil beneath them, while fissured or faulty stones were mounted in an encased setting with the bottom blackened. As natural crystals of beryl are large the gems are often extracted from the mass by expert and skilful artisans who saw the crystals into the desirable sizes.

The emerald beryl might be truly said to be a precious stone of strong individuality, for, besides its characteristic of an uneven and irregular distribution of colour, it is unique geologically, for it occurs exclusively in its primary situation, that is, in the rock in which it was formed. It is one of the minerals characteristic of crystalline schists, and is frequently found embedded in mica schists and similar rocks. The magnificent beryls found at Muzo, Colombia, however, are an exception; there the emeralds are embedded in calcite veins in limestone. Emeralds are never found in gem gravels, like diamonds, rubies, sapphires, and other precious stones.