Quality and valuation of jadeite and nephrite jade
Colour, transparency, texture, and clarity are the most important elements affecting the value of jadeite jade (Figure 9, page 5).
- Jadeite ranges in colour from white to black with intense greens, reds, and lavenders being the most sought-after. The least valuable colour is uneven black.
- The higher the transparency and finer the texture, the more valuable the jade. Transparency is described using the following scale:
• transparent (far right)
• translucent (middle)
• opaque (far left).
- Texture refers to the internal characteristics of the jadeite, which is formed by a cluster of microscopic crystals. The smaller the crystals, the more valuable the specimen.
- Clarity is based on freedom from cracks, common flaws like white, black, and brown spots, as well as grainy inclusions. The presence of different types of minerals results in black, brown, or white areas.
The evaluation of nephrite jade’s gem grade is based mainly on physical inspection of the following:
- a pleasing green colour (i.e. apple to emerald, although dark green is also used in some jewellery markets);
- good translucency (i.e. most jewellery-grade nephrite should be translucent to 4 to 5 mm in sunlight);
- good hardness (i.e. nephrite with a hardness of 6.6 to 6.8 on the Moh’s scale can achieve a higher polish that maintains its brilliance longer, as opposed to softer nephrite jade with a lower hardness of 6.3 to 6.5); and
- good clarity, namely, the lack of fractures and natural inclusions, such as black and green chromite spots and streaks.