This is fossil amber from coal mines on the island of Sumatra in Indonesia. Sumatran amber is famous for it's wide range of possible colors once it is polished. Colors range from the usual yellow-amber to a variety of colors that are rare in other ambers like red and blue. Sumatra amber also fluoresces strongly (green) under UV light.
Sumatra is millions of years old and is mined alongside coal seams, so sometimes there are small pieces of coal matrix attached to the amber. Sumatran amber has been heavily mined in recent years and now the supply is dwindling in quantity and quality. This amber I am offering was brought out of Sumatra about 20 years ago and is high quality. It is ideal for cutting and polishing.
Refer to the photos. The black centimeter cube is shown for scale and is not included. You are purchasing the specimen shown. It weighs 20 grams.