Jadeite and Nephrite

Jade includes "jadeite" and "nephrite," which are scientifically entirely different minerals. The term "jade" came into being before "jadeite." In the 16th century, indigenous people in Peru wore jade around their waists. Upon observing this, Spaniards mistook it for jewelry and named it "piedra de hijada," meaning the stone worn on the waist. This was translated into French as "pierre de l’ejade," and it is believed that the "l’ejade" part later became "jade" in English.

The Spaniards later learned that the stones served a medicinal purpose as warming stones for stomach ailments. To share this finding, they coined a phrase based on the stone's shape, "stone in the shape of a kidney." Latin translated this phrase into "lapis nephritis," which became the English "nephrite."

Until 1863, when the French mineralogist Damour discovered that jade consisted of two types: jadeite and nephrite, and that the two are completely different minerals, jade was essentially synonymous with nephrite.

Therefore, even in China, where nephrite culture had developed, jadeite was brought in from Burma after the 17th century and was confusedly referred to as jade, a situation that often still occurs today. ​

 

Jadeite, rich in jadeite pyroxene, forms only in restricted areas known as subduction zones. In contrast, Nephrite is a type of amphibole forming under standard conditions. Jedite is produced in a highly unusual low-pressure and high-temperature environment, with a pressure of 10,000 atmospheres and a temperature of 200 to 300 degrees Celsius. Conversely, Nephrite forms under about half the pressure (an estimated 5,000 atmospheres), ranging from 400℃ to 500℃. As a result, Nephrite is more abundant, with large deposits found in countries like the USA, Canada, New Zealand, Russia, China, and Taiwan. However, Jadeite is only found in a few areas worldwide, including Kachin State in Myanmar, Guatemala in Latin America, and Itoigawa in Japan. Due to its scarcity, Jadeite generally has a higher value than Nephrite.

Locations where jadeite and nephrite are found.

Fossa Magna's Gift: The Birth of Itoigawa Jade, A Geologic Wonder

Meiji-era geologist Naumann named the Fossa Magna, a Latin term meaning "large trench." This colossal trench, rather than a mere dip in the land, signifies where colliding tectonic plates sink into the earth. New strata have built up over this trench, marking the Fossa Magna area.

The Fossa Magna region's geology originates from the Neogene period around 25 million years ago. In contrast, formations to the east and west hark back over 500 million years to the Mesozoic and Paleozoic eras.

Faults that developed due to Fossa Magna's compression opened a path for magma, facilitating the surfacing of minerals and jade-containing serpentine rocks. This accessibility led to the discovery of numerous minerals in Itoigawa City, positioned on the Fossa Magna's border.

The vast depression in Japan's Fossa Magna emerged around 20 million years ago when the eastern side of the Asian continent ruptured, separating the Japanese archipelago from the mainland.

Situated directly above the Fossa Magna, Itoigawa boasts a geological structure unmatched worldwide. A series of fortunate events layered over the earth's split contributed to the creation of Itoigawa jade. Despite the region's harsh conditions, Itoigawa thrives due to the tremendous natural resources provided by active volcanic activity. This unique topography earned global recognition, leading to Itoigawa's designation as Japan's first Global Geopark in 2009.

Jade pieces often undergo artificial enhancement and treatment processes for improved color and beauty, making flawless jades available worldwide. Itoigawa jade, however, stands out with its limited production and procurement, thus simplifying the process of confirming its authenticity.

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The value of natural Itoigawa jade is determined by its rarity. Rarity refers to "items with a supply that is limited relative to their demand." Even if an item is scarcely produced, if it's not popular, it cannot be considered to have a high rarity value.

Pyramid diagram of the rarity of Itoigawa jade

Premium

Specific regions in Itoigawa yield rare jade varieties, like the blue "Irikonsawa" or the translucent, pure white "Ice Jade," produced in much smaller quantities and popular.

High Quallity

While not specifically popular, like premium grade, this unique jade possesses various colors and patterns, including deep green, lavender, and blue. At Kotaki, this grade of jade is the most commonly handled, offering a rich variation in color, transparency, and luster. Among similar colors, those typically considered of high gem quality are popular. High gem quality depends on the quality of coloration and the amount of transparency and luster.

Chart of differences in color, transparency, and luster and their popularity

Basic

This refers to jade in relatively abundant colors such as white and light green or jade that is not of particularly high gem quality. The color, luster, and transparency are subdued, making it less attractive as a gemstone. However, it possesses sufficient beauty as a piece of natural jewelry.

Jade Colors Overview

While vibrant green often defines jade, it can showcase a spectrum of other colors: red, blue, white, black, and purple. White is also the primary color of the jade pyroxene that makes up jade, and We call those unmixed, pure white pieces 'Ice Jade.' They stand as highly valuable, on par with the deep green variety.

Tea Room, Matsumoto City, Nagano Prefecture

The gallery showcases a variety of items, including magatama, bracelets, tubular beads, and small raw stones. Please note that we do not display the works from our online shop in the gallery. Please get in touch with us in advance if you wish to see a particular piece.

Access

You'll find the Itoigawa Jade Studio Kotaki gallery in Matsumoto City, Nagano Prefecture. With a convenient location, it's just a 10-minute walk from both Matsumoto Station and Matsumoto Castle. The gallery is located in a corner of a café.

2-2-5 Ote, Matsumoto, Nagano 390-0874 JAPAN
6-minute walk from Matsumoto Station, Castle Exit
(477m from Matsumoto Station)

I'd like to see the products. Where can I do that?

You can view our products on the Itoigawa Jade Studio KOTAKI website. We ship worldwide, so feel free to check it out. You also have the opportunity to see our products in person at our gallery.

I want to know more about Itoigawa jade. Where can I find that information?

You can find detailed information about the allure and history of jade in our online shop, Itoigawa Jade Studio KOTAKI.You can find detailed information about the allure and history of jade in our online shop at Itoigawa Jade Kotaki Studio.

How will the products be delivered?

If you're ordering from overseas, "World Shopping Biz" is the service we recommend. They will purchase and ship your products from Japan, delivering them anywhere. You can find more details about their purchase and shipping processes on their website.

Does it come with a warranty?

Yes, all our products come with a quality warranty.