Emeralds are capable of forming in many places in the world, including North Carolina in the United States. The reason more sources are not noted is because they do not form any notable amount of gem quality emeralds. This does not necessarily mean the sources are incapable of producing gem quality emeralds, but that they do not produce these emeralds in large quantities. More precisely, these sources do not produce commercially viable amounts of emeralds.
There are a number of reasons the source may not be viable between the quality of the gems and the labor cost of mining them. For example; Montana in the USA has one of the largest sapphire deposits in the world, but it is not more heavily mined due to high labor costs in the US.
Emeralds have a very limited color range of yellowish to bluish green, by definition of being an emerald. The color cannot be too light either, otherwise it is a green beryl. What frequently happens at major mining sites like Colombia, Zambia, Brazil, and others is that most of the gem material produced is green beryl, instead of the much more precious and expensive emerald variety. Even if the color qualifies, it is usually in such low quality the material never goes to market.
This is what happens in the most productive emerald mines. Other sites like North Carolina produce an even lower average of gem-quality material. While not impossible to produce fine-quality emeralds, the rate of finding one from non-commercial locations is very low.
While these two countries do not supply emeralds in great quantity, their quality rivals even the finest specimens. According to Sinkankas (1981), Gübelin was known to remark that some of the Pakistani emeralds were “good to outstanding” with respect to their liveliness, transparency, and color saturation, and could be favorably compared to Muzo (Colombian) stones. This is due to the fact all three form due to a hydrothermal geological process.
There is some evidence that the Afghan sources were exploited in antiquity. Current production is limited by political unrest as well as high altitudes and harsh winters in the mountain ranges they are found.
Australia does a lot of beryl ore mining, the mineral species of emeralds. Eventually emeralds were discovered in 1890 in New South Wales. After a few years of good production, the mines were closed.
Emeralds were also found at Poona in Western Australia in the early 20th century, but the life of this discovery was also short lived. The most recent attempt to rejuvenate the mining operations in Australia were centralized to Aga Khan in Western Australia in 2001, but once again, supply proved to be unsustainable and have been abandoned.
Emeralds have been known in India since antiquity, but their source is not certain. There is doubt whether the emeralds used in historic Indian jewelry were ever mined there. Tavernier (1605-1689), the famous French explorer who pioneered trade with India, disputed claims that emeralds originated in the Far East:
“As for Emeraulds, it is a vulgar error to say they come originally from the East. And therefore when jewelers and goldsmiths, to prefer a deep-coloured Emerauld enclining to black, tell ye, it is an oriental Emerauld, they speak that which is not true. I confess I could never discover in what part of our continent those stones are found. But sure I am, that the Eastern part of the world never produced any of these stones, neither in the Continent, nor in the islands. True it is that since the discovery of America some of those stones have been often brought rough from Peru to the Philippine Islands, whence they have been imported to Europe; but this is not enough to make them oriental.”
While emeralds were prized in India for many centuries, the earliest known source of true emeralds in the country were discovered in Rajasthan in the early 20th century, along with other sources. In comparison to major emeralds sources, the quality of Indian emeralds is variable. Most of the stones are low quality, being fashioned into beads and carvings for the jewelry industry.