Jade or “yu” as it is called in China, truly is one name for two separate gems with similar characteristics. The first being Jadeite, the second Nephrite, both are indeed “Jade”.
It was in 1863 when the two stones were recognized separately. Nephrite is more common, but both are tough, fine-grained rocks, suitable for carving.
Jadeite, though, made up of interlocking ,granular pyroxene crystals, occurs in a wide range of colors, such as green, lilac, white, pink, brown, red, blue, black, orange and yellow. The most prized variety, imperial jade, is a deep rich emerald green due to chromium content. Jadeite commonly has a dimpled surface when polished.
Nephrite is found as aggregates of fibrous amphibole crystals. This composite forms an interlocking structure that is tougher than steel. Colors may vary from a dark green (which is rich in iron) to a cream color (which is high in magnesium). Nephrite jade may be homogeneous in color, banded or blotchy.