Fossilized tree sap which is transparent, most commonly orange (but it can be white, green, black, or violet) and worn as a gemstone. The best supplies are from the areas near the Baltic Sea. Very lightweight compared to some gems, so large pieces can be worn comfortably. Supposed to give off an odor of musty pine when heated. Sometimes bits of plant or animal material are fossilized inside the sap (hence the plot of "Jurassic Park," which made that type of amber very popular for a few years).