Aquamarine General Information
In the beryl species, aquamarine is second only to emerald in popularity. Fine aquamarines are combined with diamonds and set in platinum in this jewelry set.
The name “aquamarine” is derived from two Latin words: aqua, meaning “water” and marina, meaning “of the sea.”
On the commercial market, aquamarine competes with treated blue topaz for attention, but fine aquamarine sells for much more than treated blue topaz of equivalent quality. In early 2012, wholesale prices for a good-quality 3-carat 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 range of aquamarine is very narrow: it can be blue, very slightly blue-green, blue-green, very strong blue-green, or blue-green.
Despite Sapphire The most popular blue gemstone, aquamarine is one of many other blue stones that have considerable markets of their own. However, even in its darkest shades, aquamarine rarely matches the blue of sapphire.
Like most beryls, well-formed aquamarine crystals are usually six-sided columns with flat faces at their ends.
Court:
The cutters align the facet of the table parallel to the length of the glass. The gem is pleochroic and shows a strong, almost colorless blue in different directions of the crystal. Fortunately, the pleochroic blue color matches the most weight-retaining cut orientation. Cutters often model aquamarines as emerald cuts or as round or oval brilliants. The rough is quite abundant, so there are usually well-cut stones. 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 over 25 cts.
Modern aquamarines often have to be quite large, usually over 5 carats, to show rich, 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 cts. For this reason, smaller stones of the superior color can sell for more per carat than larger stones of the same color.
Clarity
Most faceted aquamarines are eye clean. Some crystals may contain liquid inclusions, but clarity features are few or absent in most finished gems.
Imitations and synthetics of aquamarine
Russian growers produce synthetic hydrothermal aquamarine, but it is not widely available. The most common aquamarine imitations are treated blue topaz, pale blue glass, cobalt colored synthetic blue spinel.
Separating natural aquamarine from all the other imitations can be quite easy. Standard gemological testing like refractive index and Chelsea filter easily distinguish aquamarine from its imitators.
Today’s aquamarine fountains and market
Brazil
Brazil has been the world’s 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 was the first large aquamarine crystal ever recorded. Millions of carats of fine aquamarine have been found in the region’s thousands of mines. The largest recorded aquamarine crystal was found in 1910, in Minas Gerais, Brazil. 244 lbs (110 kg) 19 in. (48 cm) long and 15 in. (38cm) diameter
Although the thin blue-green glass was water-worn, most of it was gem-quality and so transparent that people could read the printed pages along 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 find 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, alluvial deposits produce most of the material. Historically, aquamarine and other gems have been found in riverbeds or excavated from the ground by independent miners called garimpeiros. Because the new laws make it difficult for the garimpeiros to operate, the recovery method has changed to mechanized open pit mining.
There are no precise production figures for Brazilian gems because official records are not kept. Trade sources estimate, however, that less than 5 percent of Minas Gerais’ yield consists of top-grade dark blue stones.
Pakistan
Pakistan is another major producer of aquamarine. Pegmatites produce light green and blue crystals, some up to 12 inches. (30 cm) long by 5 in. (12cm) wide. Miners also find inky blue crystals.
Porcelain
China recently became the world’s leading producer of commercial-grade small aquamarine. Most stones are around 6x4mm, with commercial grade sizes rarely exceeding 10x8mm, or around 2 carats. Crude mining techniques damage many crystals, and the yield of gem-quality crystals is only 10 to 15 percent. Some members of the trade say that if Chinese miners were more careful, they could produce larger stones with a deeper color.
Chinese aquamarine has replaced the Brazilian material in most mass-marketed 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 top quality gems.
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 marketable in the US.
Nigeria
Nigeria has been 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 favored 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 to have been unearthed. Material in Mozambique may possess a particularly rich blue hue cut aquamarine that is a true treasure from this area.
From Mozambique “Santa Maria colour” Aqua has a very fine natural blue. Furthermore, it has been distinguished from aquamarine from other localities by the ability to maintain a strong color even in small stones. The pegmatite-rich pocket containing beryl gems is frequent and extends throughout the African continent. It seems to me that for a short time, we will expect to see more aquamarine production from many parts of Africa.
Less important sources are Australia, Kenya, the US and Zambia.
Aquamarine Treatments
Virtually all of the blue color in aquamarine is derived from the heat treatment of bluish-green, yellow-green, or even brownish-yellow colored gems. The controlled heating process can remove the yellow color component and leaves a purer blue hue in the stone.
Heat treatment:
It is standard practice to cut the rough stones and then heat the shaped 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, treaters heat the aquamarine to between 482ºF and 1292ºF (250ºC and 700ºC) for varying periods of time. Treaters heat stones with significant inclusions for longer periods at lower temperatures. In most cases, heat treatment on aquamarine cannot be detected and the treated color appears to be permanent.
Some dealers, however, leave blue-green aquamarine untreated and use its uniqueness to promote it. Its untreated color sets it apart from its competitor, treated blue topaz. Some traders see the saturated market for blue topaz as a sign of good times ahead for aquamarine. And with today’s widespread concern about treatments, untreated gemstones like naturally colored aquamarine are attracting more consumers than ever before.
