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Introduction:
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Emerald is the most precious member of the beryl group. Unlike many other stones, inclusions in emerald are not considered faults. Rather, they are good indication of the stone's authenticity and can give clues concerning it's source. Colombia, Zambia, Brazil, Pakistan, Zimbabwe and Afghanistan are sources for emeralds. While emerald is a relatively hard stone, rated 7 ˝-8 on the Mohs' scale, it is not tough and should be used accordingly in jewelry. For instance, emerald rings do not make the best choices for everyday wear. Nonetheless, the May birthstone is a very popular choice for consumers and adds extensive beauty and charm to any jewelry collection. The tradition of cutting emeralds with a step cut, better known as the emerald cut, does provide some protection against knocks. Keep emeralds on-hand year round because of their popularity. |
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History
of...
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Emerald is one of the many gemstones that supports extensive dialogue over which source is best. The two major competitors when it comes to emerald are Colombia and Zambia. Colombian emerald enjoyed many years of undisputed fame as the best material available, but in 1976, geologists discovered astonishingly clean deposits of emerald in Zambia. The stones vary in composition, accounting for color subtleties and variation. The same differences in composition often reveal a stone's source. Because of emerald's popularity among consumers, there is little room to quabble about a stone's origin these days. Beautiful stones from all over the world can be respected for their beauty and value. In fact, there are many famous emeralds with values that rival famous diamonds and rubies. One example is a Viennese jug that weighs 2205 ct and is 4 1/4 inches tall.
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Technical
Specifications:
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| DESCRIPTION |
| Emerald is the most precious member of the beryl group. |
| Chemical
Composition: |
Be3Al2Si6O18 |
| Appearance: |
•Transparent; Highly included stones may be translucent
•Light to very dark green to very strongly bluish green |
| Misnomers: |
None known |
| Typical
Sizes: |
Melee sizes to 4 carats; faceted stones over 100 carats are known |
| Cut Styles: |
Faceted (emerald cut common), cabachons, carvings |
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| IDENTIFICATION |
| Optic
Character: |
DR, uniaxial negative |
| Refractive
Index: |
1.577-1.583 (+/-.017) |
| Birefingence: |
.005 to .009 |
| Dispersion: |
.014 |
| Pleochroism: |
Moderate to strong, green and bluish green |
| Ultraviolet
Fluorescence: |
Usually inert but may fluoresce orangy red to red in very fine colors (LW and SW; LW stronger); oiled emerald--oil in fractures may fluoresce yellowish green to greenish yellow (LW), weaker to inert (SW) |
| Absorption
Spectra: |
Distinct lines at 683 and 680.5 nm, less distinct lines 662 and 646, partial absorption between 630 and 580 nm and almost complete absorption of the violet |
| Cause
of Color: |
Usually chromium; Some are colored by vanadium, or by both chromium and vanadium |
| Specific
Gravity: |
2.72 (+.18, -.05) |
| Polish
Luster: |
Vitreous |
| Fracture: |
Conchoidal |
| Luster: |
Vitreous to resinous |
| Cleavage: |
Very difficult in one direction, almost never seen |
| Indentifying
Characteristics: |
3-phase inclusions (especially in Colombian stones); calcite, pyrite, and mica inclusions; tremolite needles |
| Known
Enhancements: |
Emeralds with internal breaks that reach the surface are routinely oiled to deepen their color or improve transparency. The oil will likely dry out or discolor over time. |
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| DURABILITY RATINGS |
| Hardness: |
7 1/2 to 8 |
| Toughness: |
Poor to good |
| Emerald is sometimes mistaken for: Aventurine, demantoid, diopside, dioptase, fluorite, grossular, hiddenite, peridot, uvarovite and verdelite |
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Care
Tips:
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| Cleaning Methods |
| •Ultrasonic: |
Never |
| •Steamer: |
Never |
| •Warm
soapy water: |
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| Stability of Stone |
| •Heat
tolerance: |
Exposure to heat may cause additional fracturing or complete breakage |
| •Light
tolerance: |
Emerald is stable when exposed to light, but fading may occur in stones oiled with green oil |
| •Chemical tolerance: |
Emerald is resistant to all acids except hydrofluoric; Solvents may dry out oil |
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Recommended
Uses:
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Rings
- Although emeralds are popular in ring mountings it is not the safest use of the stone. Emeralds are susceptible to the common exposure to abuse and substances a ring encounters. For example: hand washing will dry out an emerald rendering it brittle. Awareness of the delicate nature of emeralds will prevent most common dangers. For the careful ring wearer, no other colored stone will match the unique beauty and pleasure of an emerald. Earrings
- Emeralds work well for earrings. They are generally safe from too much abuse or exposure to harmful substances and are beautiful. The only thing to consider about using for earrings is the cost of emeralds. Emeralds are generally more expensive than most colored stones available and are not easily replaced if lost as often occurs with earrings.
Pendants - Emerald pendants are both beautiful and safe. Pendants are probably the best option for emeralds. Large stones are available and make for one of the most desirable pieces of colored stone jewelry. For the emerald admirer a pendant is highly recommended.
Bracelet - Based on cost and abuse emeralds are not necissarily suited for bracelet use. Although commonly found in bracelets, the delicate nature of the stone and relatively expensive price of emeralds does not lend itself well to a bracelet. However, an emerald admirer with their heart set on a bracelet can fulfill their desires but need to be aware of the care needed to protect their investment.
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Source
Map:
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| All technical specifications and care
tips on this page was referrenced from the "Gem
Reference Guide" published by the Gemological Institute
of America |
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