Amber Quality Factors
Although consumers are most familiar with yellow and golden amber, the gem can be white, yellow, and orange to reddish brown. Reddish amber is more valuable than golden amber, which is more valuable than yellow amber. Rarely, strong fluorescence can give amber a bluish or greenish appearance, which can be highly valuable when attractive. Oxidation can cause the material to change colour over time.
Cutting and polishing amber for jewellery makes it more susceptible to oxidation by removing or thinning the harder exterior surface. Fine translucent yellow or orange amber can gradually darken to reddish brown and eventually black.
The colour of amber can be modified by heat treatment and dyeing.
Transparent amber is more valuable than cloudy material. An interesting plant or animal inclusion adds to the value of an amber specimen.
Treatment by careful heating in rapeseed (canola) oil can clarify cloudy amber somewhat. The resulting amber sometimes exhibits crack-like circular marks called sun spangles.
Amber is commonly polished into a free-form shape that follows the original shape of the rough. It might then be set into jewellery or drilled for stringing. Cutting styles for amber include beads, cabochons and free-form polished pieces. Amber might be faceted, but this is rare.
Amber has a lower relative density than salt water so it can feel very light, even in large sizes. This makes it possible to use fairly large pieces in amber jewellery.