Emerald

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File:Vintage Emerald Ring.jpg
5.11 Carat Vintage Emerald Ring.
Photo Courtesy of Lang Antiques.

The color of emerald, the birthstone for the month of May, has been described as the "warm green of a meadow in spring"[1]. Its grass green primary hue is usually modified by slight bluish or yellowish undertones. A vivid, slightly bluish green is the most desirable color. The most valuable emeralds are top quality stones from Colombia, unrivaled in their - chromium induced - silky hue of green.

This illustrious and most esteemed member of the beryl family has long been regarded as one of the most precious of all gemstones, surpassed only by ruby. Cellini in the 16th century remarked that the value of a fine emerald would be half the price of a like ruby, but was four times more valuable than diamond[2].

Emerald is a type III gemstone on the GIA clarity scale as they are usually quite included. The vast majority of emeralds have been treated to improve their clarity and appearance, a practice that has been widely accepted for centuries. Cedar oil, a natural and colorless oil with a refractive index similar to emerald, is the most common and accepted method of treatment, providing a stable and reversible effect.

French Straight Line Emerald Bracelet.
Photo Courtesy of Lang Antiques
Gemological information for emerald
Color Green with blue or yellow tones
Crystal Structure Hexagonal
Family Beryl
Refractive Index 1.566-1.600
Durability May be fragile/brittle
Hardness 7.5-8
Similar stones Confusion is Possible with Tourmaline, Diopside, Fluorite and Green Glass
Treatments Emerald is Routinely Fracture Filled and/or Oiled
Country of origin Brazil, Colombia, Africa
Emerald care
Ultrasonic cleaning Not safe
Steam cleaning Not safe
Warm soapy water Safe
Chemical attact Usually resistant
Light sensitivity Stable
Heat sensitivity Very sensitive, unstable

Notes

  1. Hermann Espig, 1960
  2. Cellini, p.23

Sources consulted

  • The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture, Ashbee, C.R.. ISBN 0486215686

Online G&G articles on emerald

Lang Antiques
Lang Antiques