Emerald
from the Antique Jewelry University
The color of emerald, the birthstone of the month May, has once been described as "warm green of a meadow in spring"[1]. It's grass green primary hue is usually modified by slight bluish or yellowish undertones. The greener the color, the more desirable the stone becomes and top quality stones from Colombia are unrivaled in their - chromium induced - silky hue.
This high-end variety 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 narrated that the value of a fine emerald would be half the price of a like ruby, but was four times more valuable than diamond[1].
Emerald is a type III gemstone on the GIA clarity scale, meaning they are usually included with imperfections which may detract from their beauty. It is a longtime practice that these stones are impregnated with oils to mask these internal features. Polymer and resin type fillers are also used to reduce the visibility of the fine fissures that reach the surface and therefor improve clarity. This is a common practice that has been widely accepted for centuries and as always; beauty is forgiven many flaws. Only few emeralds have undergone no treatment and those command extremely high prices.
Image 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
Sources consulted
- The Treatises of Benvenuto Cellini on Goldsmithing and Sculpture, Ashbee, C.R.. ISBN 0486215686
Online G&G articles on emerald
- Nov.-Dec. 1934, Emerald mining in Colombia, p. 149, 6pp.
- Spring 1938, South African emeralds, p. 146, 1p.
- Summer 1940, Differences Between Russian and Colombian Emeralds, by Gübelin, p. 89, 4pp.
- Spring 1941, The Emerald Mines of Muzo, Colombia, p. 130, 5pp.
- Winter 1943, "Indian emeralds"–crackled quartz, dyed, p. 118, 1p.
- Summer 1945, A cat's-eye emerald, p. 222, 1p.
- Fall 1947, The 2,226 gram Emerald of Iakov I. Kakovin, p. 469, 2pp.
- Winter 1947, The Emerald in Fable and History, p. 497, 3pp.
- Spring 1948, Recent Emerald Production of Colombia, p. 25, 2pp.
- Spring 1951, Data on Indian Emeralds, by Gübelin, p. 13, 10pp.
- Summer 1950, Emerald mine report from Colombia, p. 316, 1p.
- Summer 1950, Emeralds mined in India, p. 321, 1p.
- Fall 1950, Indian Emeralds, by Webster, p. 344, 2pp.
- Winter 1950, Report of Chivor emerald mines, p. 376, 3pp.
- Fall 1955, The new Gachala emerald mine in Colombia, p. 195, 2pp.
- Summer 1956, The Emeralds from Habachtel, Austria, by Gübelin, p. 295, 15pp.
- Fall 1958, The New Emeralds from Sandawana, Southern Rhodesia, by Gübelin, p. 195, 9pp.
- Fall 1958, Sandawana Emeralds-Some Commercial Aspects, p. 221, 3pp.
- Spring 1959, A near flawless and beautiful color emerald 12.65 cts., p. 264, 2pp.
- Spring 1959, Another Emerald Deposit Found in Rhodesia, p. 284, 1p.
- Fall 1960, An oxidation layer seen on old emeralds, p. 70, 1p.
- Spring 1961, A New Emerald Find Near Borur, Colombia, p. 142, 2pp.
- Winter 1961, Brazilian pegmatite emerald and its absorption spectrum, p. 244, 1p.
- Winter 1961, New Data on New Deposit of Australian Emeralds, by Gübelin, p. 251, 1p.
- Winter 1963, A New Source of Emeralds in Brazil, by Draper, p. 111, 5pp.
- Fall 1964, Trapiche Emeralds from Colombia, p. 210, 5pp.
- Winter 1964, Chromeless emeralds from Brazil identified as emeralds by GIA, p. 244, 1p.
- Spring 1965, Trapiche emeralds from Colombia, p. 265, 3pp.
- Summer 1967, Trapiche emeralds from Colombia in large sizes, p. 181, 2pp.
- Fall 1967, Black-core emerald crystals, p. 799, 3pp.
- Fall 1967, A new emerald source in Australia, p. 220, 4pp.
- Spring 1968, The black material in trapiche emeralds, p. 287, 2pp.
- Summer 1968, Inclusions in Russian and Colombian emeralds, p. 305, 3pp.
- Summer 1968, Trapiche emeralds, p. 316, 2pp.
- Summer 1968, Zambia emeralds, p. 320, 1p.
- Spring 1969, Notable Emeralds in the Crown Jewels of Iran, by Meen, p. 8, 3pp.
- Spring 1969, Changes in synthetic emeralds, p. 23, 2pp.
- Summer 1969, Russian emeralds, p. 63, 2pp.
- Summer 1969, First fluorite inclusion seen in emerald, p. 53, 2pp.
- Summer 1970, Natural etched trapiche crystal left on girdle, p. 187, 2pp.
- Summer 1970, A 7 ct. faceted trapiche emerald, p. 195, 1p.
- Fall 1970, 3-phase inclusions, with two bubbles, found in Colombian emeralds, p. 235, 2pp.
- Winter 1970, North Carolina emeralds, p. 251, 3pp.
- Spring 1971, 2-phase inclusions in Colombian emeralds, p. 275, 1p.
- Spring 1971, Trapiche emeralds, inclusions and high R.I., p. 277, 1p.
- Winter 1971, New type inclusions in natural emeralds, p. 379, 2pp.
- Spring 1972, A heat-wave pattern inclusion in natural emeralds, p. 18, 2pp.
- Summer 1972, Unusual quartz inclusions in North Carolina emeralds, p. 34, 4pp.
- Summer 1972, New emerald find from Marua District, Mozambique, p. 52, 2pp.
- Fall 1972, Muzo Emerald Mine, Colombia, p. 77, 5pp.
- Fall 1972, A plane of pyrites in a Colombian emerald, p. 93, 2pp.
- Spring 1973, Parisite in Muzo emeralds and Trapiche emeralds, p. 148, 2pp.
- Winter 1973, Heavy concentration of pyrites in a Colombian emerald, p. 253, 2pp.
- Spring 1975, A helical inclusion in emerald, p. 28, 1p. (See also Fall 1983, p. 173, 1p.)
- Fall 1975, Color zoning in an emerald, p. 73, 2pp.
- Summer 1976, Included rutile needles in emerald, p. 174, 1p.
- Fall 1976, A quartz crystal inclusion in Colombian emerald, p. 213, 1p. (See also Summer 1977, p. 314, 1p.)
- Fall 1977, Very strong color zoning in emerald, p. 328, 2pp.
- Fall 1977, Colombian Emeralds, by Sinkankas, p. 334, 4pp.
- Winter 1977, A Puzzling Natural Emerald and “Ferrer” glass imitation emeralds from the 1920’s, p. 366, 1p.
- Fall 1979, Tripache Emerald, p. 211, 1p.
- Winter 1980, Unexpected Absorption Spectrum in Natural Emeralds, p. 391, 2pp.
- Winter 1980, Mobile Bubble in A Three-Phase Emerald Inclusion, p. 392, 3pp.