Aquamarine General Information
In the beryl species, aquamarine ranks second after emerald in popularity. Fine aquamarines are paired with diamonds and set in platinum in this jewelry set.
The name “aquamarine” is derived from two Latin words: aqua, which means “water” and marina, which means “from the sea.”
In the commercial market, aquamarine competes with treated blue topaz for attention, but fine aquamarine sells for much more than equivalent quality treated blue topaz. As of early 2012, wholesale prices for a good quality 3-carat size stone of African origin ranged from $ 65 to $ 120 per carat, depending on the degree of color saturation.
Aquamarine’s hardness and transparency make it popular with designers, artists, and carvers. Gem sculptors use aquamarine for fancy cuts and ornamental objects.
The color gamut of aquamarine is very narrow: it can be blue, very slightly greenish blue, greenish blue, very greenish blue or greenish blue.
Although Sapphire The most popular blue gemstone, aquamarine is one of many other bluestones that have significant markets of their own. However, even in its darker shades, aquamarine rarely matches sapphire blue.
Like most beryl, well-formed aquamarine crystals are typically six-sided columns with flat faces at their ends.
Court:
The cutters align the facet of the table parallel to the length of the crystal. The gem is pleochroic, showing an intense blue and almost colorless in different crystal directions. Fortunately, the pleochroic blue color matches the cutting orientation that retains the most weight. Cutters often model aquamarines as emerald cuts or as round or oval brilliants. The rough is quite abundant, so there are generally well-cut stones available. Aquamarine crystals can range from very small to very large, up to 100 pounds. (45 kg) in some cases. Large stones are readily available, but it is difficult to use very large stones in jewelry, so there is less demand for them. As a result, prices per carat tend to decrease for sizes greater than 25 carats.
Modeled aquamarines often have to be quite large, usually over 5 carats, to show a deep, dark color. Although small gems are rarely saturated enough to be attractive, stones from some mines in Africa (Nigeria, Madagascar, and Mozambique, for example) are known for their intense color in sizes less than 5 carats. For this reason, smaller stones of the top color may sell for more per carat than larger stones of the same color.
Clarity
Most faceted aquamarines cleanse the eyes. Some crystals may contain liquid inclusions, but clarity characteristics are few or absent in most finished gemstones.
Imitations of aquamarine and synthetics.
Russian producers produce hydrothermal synthetic aquamarine, but it is not widely available. The most common imitations of aquamarine are treated blue topaz, pale blue glass, synthetic blue spinel colored with cobalt.
Separating natural aquamarine from all other imitations can be quite easy. Standard gemological tests such as the index of refraction and the Chelsea filter easily distinguish aqua from its imitators.
Today’s aquamarine fountains and market
Brazil
Brazil has been the most important source of gem-quality aquamarine since 1811, when a miner found a large aquamarine crystal in a river bed near Teófilo Otoni. He weighed about 15 pounds. (7 kg), and it was the first large aquamarine crystal ever recorded. The largest aquamarine crystal on record was found in 1910, in Minas Gerais, Brazil. 244 lbs. (110 kg) 19 in. (48 cm) long and 15 in. (38 cm) in diameter
Although the fine blue-green glass was water-worn, most of it was gem-quality and so transparent that people could read the printed pages across the glass.
When German immigrants settled in Brazil around 1850, they discovered that they could dig almost anywhere, with almost any type of equipment, and extract aquamarine crystals. Someone sent samples to Idar-Oberstein, Germany, then as now a major cutting center, for examination. That was the beginning of a close gemstone mining and trading relationship between Brazilian miners and German cutters.
Most of the aquamarine mines are located in the northeast of Minas Gerais. Although some darker crystals come directly from the pegmatite, the alluvial deposits produce most of the material. Historically, aquamarine and other gems have been found in riverbeds or mined from the ground by independent miners called garimpeiros. Because new laws make it difficult for garimpeiros to operate, the recovery method has been changed to mechanized open pit mining.
There are no precise figures for Brazilian gem production because no official records are kept. Commercial sources estimate, however, that less than 5 percent of Minas Gerais’s yield consists of high-quality dark blue stones.
Pakistan
Pakistan is another major aquamarine producer. Pegmatites produce light green and blue crystals, some as large as 12 in. (30 cm) long by 5 in. (12 cm) wide. Miners also find inky blue crystals.
porcelain
China recently became the world’s leading producer of commercial grade small aquamarine. Most stones measure around 6x4mm, and commercial grade sizes rarely exceed 10x8mm, or around 2 cts. Raw mining techniques damage many crystals, and the yield of gem-quality crystals is only 10-15 percent. Some members of the trade say that if Chinese miners were more careful, they could produce larger stones with a more intense color.
Chinese aquamarine has replaced the Brazilian material in most of the massively traded jewelry available through home shopping networks and other high-volume outlets.
The introduction of treated blue topaz in the 1980s had a negative effect on the aquamarine market in the United States, but not elsewhere. Consumers in Japan and Europe preferred aquamarine and were willing to pay high prices for high-quality gemstones.
In the late 1990s, Japan was the best market for high-quality aquamarine. Medium to high quality stones also sold well in Germany and Italy, and almost all grades were marketed in the USA.
Nigeria
Nigeria is known to be a source of aquamarine producing large, clean material since the early 1990s. Generally speaking, most of the characteristic colors of Nigerian aquamarine are light greenish blue to blue and fairly uniform in color. This makes them favorable among many television shopping networks that produce silver jewelry for the mass market.
Mozambique and Madagascar
The Madagascar and Mozambique deposits are the most recent discovery of high-quality, dark-colored aquamarine ever unearthed. The material in Mozambique can possess a particularly rich blue tone cut, aquamarine is a true treasure of this area.
From Mozambique “Santa Maria color” Aqua has a very fine natural blue. In addition, it has been distinguished from aquamarine from other localities by the ability to maintain a strong color even on small stones. The rich pocket of pegmatites containing beryl gems is prevalent and is spread throughout the African continent. It seems to me that for a short time, we will expect to see more aquamarine production in many parts of Africa.
The least important sources are Australia, Kenya, the US, and Zambia.
Aquamarine treatments
Virtually all of the blue color in aquamarine is derived from heat treatment of bluish-green, greenish-yellow, or even brownish-yellow gems. The control heating process can remove the yellow component and leave a more pure blue cast on the stone.
Heat treatment:
It is standard practice to cut the rough stones and then heat the molded stones. Because aquamarines are largely free of liquid inclusions, they respond well to heat treatment. Depending on the mine of origin and the clarity of the stones, the treaters heat the aquamarine between 482ºF and 1,292ºF (250ºC and 700ºC) for varying periods of time. Treaters heat stones with significant inclusions for longer periods at lower temperatures. In most cases, the aquamarine heat treatment cannot be detected and the treated color appears to be permanent.
Some merchants, however, leave the blue-green aquamarine untreated and use its uniqueness to promote it. Its untreated color distinguishes it from its competitor, the treated blue topaz. Some traders see the saturated market for blue topaz as a sign of good times ahead for aquamarine. And due to the current widespread concern about treatments, untreated gemstones, such as natural-colored aquamarine, are attracting more consumers than ever.