Jade is a term referring to jadeite and nephrite. Jadeite and nephrite are two different types of jade.
Jadeite is commonly known as Burmese jade. It is a material composing mainly of sodium aluminum silicate (NaAlSi2O6).
Jadeite can appear as natural jadeite and treated jadeite.
Natural jadeite, also known as Type A jadeite, is jadeite that is 100% natural in colour and composition. It also means that the jadeite is untreated. A jadeite has to meet the following conditions before it can be called natural jadeite (Type A). These conditions include (1) a reflective index of 1.66 to 1.68. (2) A specific gravity of 3.32 to 3.35 g/cm3. Treated jadeite may have specific gravity of 3.3 or less. (3) Magnification Test should reveal fibrous and granular structure. (4) Absorption spectrum should reveal that the jadeite has not been dyed. (5) Fluorescence test using ultraviolet light treatment should reveal that the jadeite does not release any ultraviolet light. Treated jadeite subject to ultraviolet light would release strong blue light. (6) Infrared spectrum test should reveal that the jadeite has not been treated with polymer or excessive wax.
The only sure way to know whether a jadeite is natural (Type A) is to have it certified by a gemologist. A natural (Type A) jadeite has to meet those mechanical and optical properties listed above. These properties can only be determined by a gemologist using equipments.
There are two factors that make icy jadeite more expensive than non-icy jadeite. The first factor is that icy jadeite is more mesmerizing than non-icy jadeite because of the translucency. The second factor is that icy jadeite is rarer than non-icy jadeite.