Among the varieties of the mineral beryl are included some of the most important gemstones. Emerald and aquamarine are both prominent in the world of gems and golden beryl and morganite provide exceptionally attractive stones that are potentially important. Emerald is certainly one of the most valuable gems one that has always been included in lists of the few "precious stones".
Emerald
Medium light to medium dark tones of green beryl are called emerald. Stones that are light or very light green are properly called green beryl rather than emerald. Since it has been used for many years, the usual trade classification based on geographical location is given below for information, but with the recommendation that the grading system on the price chart later in the assignment replaces the locality terminology.
Colombian Emeralds
The finest emeralds have always come from this South American republic. Relatively clear pure green, slightly yellowish or slightly bluish-green stones are called Colombian emeralds. Actually, the average output from the Muzo, Chivor, Cosquez arid Gachala mines differs and each, produces a range of qualities. A fine emerald may be referred to as Colombian, regardless of source, or it may be called a Muzo, Chivor etc. Muzo produces the finest colors, but the stones are usually more heavily flawed than those from Chivor.
Russian, or Siberian Emeralds
The emeralds produced by the mines of the Ural Mountain area are characteristically more yellowish green, more heavily flawed, and slightly lighter in color than Colombian stones.
Brazilian Emeralds
Most of the green material produced in Brazil is more properly classified as green beryl, but some stones are sufficiently deep in tone to be called emerald. This pegmatite material is usually almost free from flaws. Heavily flawed crystals are found in micaschist in Brazil, but they are not ordinarily designated Brazilian emeralds in the trade.
Sandawana Emeralds
These emeralds found in a schist bordering a pegmatite in the Belingwe Native Reserve country of Rhodesia are marketed under the name Sandawana emeralds. The color of this best quality material is a fine deep emerald green, but owing to the flawed nature of the crystals, cut stones over a quarter of a carat in weight are rare.
Aquamarine
The term aquamarine is applied accurately to blue to greenish blue to bluish-green beryl; most commonly. the color is greenish blue. The tone varies from very light to medium dark.
Madagascar Aquamarine
Stones from Madagascar are frequently a medium dark blue, compared to the usual color, and any aquamarine that has this color is referred to as a "Madagascar."
Brazilian Aquamarine
Bluish-green stones are usually referred to as Brazilian aquamarines. (Note: This is also a misleading name that has been used for similarly colored topazs)
Golden Beryl
Beryl with a brownish-yellow color, sometimes referred to as "ginger brown" is called golden beryl. Stones in the yellow to brown color range are sometimes referred to as heliodor (HE-Iee-oh-door) by mineralogists, a name that is derived from two Greek words meaning "sun" and "gift".
Morganite
Light purple-red to light purplish-red beryl is called morganite. Sometimes, light orange-red stones are also included under this term.
Other Transparent Varieties
Beryl also occurs in other colors, such as greenish yellow, orange and colorless. The colorless variety, which is rarely used for gem purposes, because it is too low in R.I. and dispersion to have much "life" is sometimes called goshenite (GO-shen-ite). The name is derived from Goshen, massachusetts, where it has been found. The greenish-yellow material is often called chrysolite aquamarine, because it resembles the variety of peridot with that color. The rich, medium tone of orange has never been given a separate name. Although it is rarely encountered, it is a very interesting stone in appearance no other gemstone has a color that resembles an orange beryl. Red beryl of medium tone was discovered in Utah in 1970, but too little transparent material was found to make mining pay.
Cat's-Eye Beryl
Chatoyancy sometimes occurs in semitransparent beryl of various colors. Although some of this material is cut into cabochons to bring out the cat's-eye effect. It is usually too weak to be of any major importance as a competitor to chrysoberyl cat's-eye. It is particularly likely to occur in aquamarine and morganite, although a 7 carat cat's eye emerald in the Smithsonian Institution has merit. The Smith sonian also has a handsome orange beryl cat's-eye.
Star Beryl
On occasion, dark yellow-brown to black beryl with a rather poor star is seen. It is sometimes confused with black star sapphire, but it is not very commonly used for gem purposes.
