Besides the classic brown, red and yellow hues, amber is found in a wide range of colours. Milky colours develop due to the enclosure of tiny bubbles or organic substances. Baltic amber can even be completely opaque white.
Sometimes, amber shades are so dark that they appear black. This occurs when the piece contains a lot of plant debris or the organic matter is tightly packed. Green hues are rare in Baltic amber, and opinions vary as to why they occur. Possible theories: the inclusion of decaying plant matter or finely distributed mineral deposits in the piece of amber, which dulls the natural colour. Another rare variety, blue Baltic amber, is thought to be caused by reflections and interferences of light on the surface and in the interior of the amber.
Apart from more or less solid colours, amber also appears in striking colour combinations, such as white/yellow/black or yellow/red/white.
Weather-beaten amber often has a thin outer crust which ranges from orange and red to brown in colour. The amber beneath this shell retains its original colour, unless the outer tones are able to seep inside through fissures in the amber.