Nephrite jade ranges in color from creamy white to deep green, deep emerald green form of nephrite jade is the most valuable and desired. Identifying raw or rough nephrite jade requires a basic understanding of its properties and characteristics. With some simple tests, you can quickly determine if a stone is indeed nephrite jade.
Examine the Color
The first step in identifying nephrite jade is to look at its color. Genuine nephrite jade will always be some shade of green, from very pale sea foam greens to deep dark spinach greens. The most prized color is a vivid emerald green. While white nephrite does occur, other colors like reds, purples, blacks, and browns are not true nephrite jade. Be wary of jade imitations that have been dyed to achieve these non-green colors.
Check the Texture
The texture of nephrite jade is quite distinct. It has a smooth, matte appearance and a greasy or waxy feel when touched. There should be no pits, cavities, cracks, or granular areas on the surface. Scratch the surface with a knife to see if any powder comes off, which would indicate a fake stone. Real jade will not powder when scratched. Nephrite is also cool and smooth to the touch. These textural properties distinguish jade from cheap serpentine imitations.
Test the Density
Nephrite jade is very dense and heavy for its size. Heft the stone in your hand to gauge its weight. Nephrite will feel noticeably heavy, with a specific gravity usually between 2.9 and 3.3. This allows it to take a high polish and maintain its smooth surface. Compare the weight to other stones like quartz, marble or serpentine, which have a lower density. You can also use a jewelry scale to test its exact specific gravity.
Examine with Bright Light
When illuminated with a bright flashlight or lamp, nephrite jade will appear almost translucent. Light is able to penetrate the stone because of its tightly intergrown fibrous structure. Examine it from different angles to see this effect. The light will reflect off various mineral grains and strands of jadeite tremolite fibers inside the stone. Mindat.org notes that a "greasy or waxy" luster will be visible when light reflects from the surface.
Check for Impurities
Nephrite jade often contains impurities that appear as small dark specks or blotches within the stone. These can look like dark patches or dots when the stone is illuminated. The impurities help prove the stone is natural rather than artificially colored and treated. However, avoid stones with excessive impurities as they will be less valuable and attractive. Some speckles and flaws are expected but large dark blotches will diminish the beauty.
Perform a Scratch Test
A simple scratch test can help determine if a stone is really nephrite jade. Find a piece of glass, granite, unglazed ceramic or steel. Then try to scratch the surface of the jade with the other material. Because nephrite jade scores a 6.5 to 7 on the Mohs hardness scale, it can be scratched by most metals, granite or glass. If the supposed jade scratches easily, it is likely a fake made of softer material. Quartz and jadeite can scratch nephrite as they are higher on the Mohs scale.
Listen for a Bell-Like Ring
When struck, nephrite emits a musical, bell-like ringing sound. This quality is known as lithophony. Gently tap the jade on a hard surface while listening closely. The tone should resonate for a few seconds with a clear chime or ringing sound. Nephrite produces a different tone from metals or glass. You can also compare it to the sound of striking serpentine or other stones.
With a basic understanding of its physical and visual properties, identifying raw or unpolished nephrite jade is relatively straightforward. Look for the distinctive greasy luster, cool smooth texture, emerald green color, translucency, high density and bell-like ringing sound. Perform simple scratch, density and sound tests to confirm the stone is real jade. With practice, you will be able to spot authentic nephrite jade even in rough unpolished forms.
