Fluorescent black amber is the fossilised form of biological material, tree sap, it is estimated to be from the Tertiary Period, making it between 15 to 25 million years old, making it younger than world famous Baltic amber,but still older than copal. However, this particular variant has other interesting features, it's almost opaque and has a brown glassy texture, it is a variant known as glessite, which is actually harder than Baltic amber. It also has excellent fluorescent properties, when exposed under shortwave UV lighting, it shines a pale green/yellow colour with some inclusions of blue, the complete opposite of its colour under natural light. This has made this variation of amber much sought after around the world. The specimens are found in prehistoric coal measures in the Indonesian region, these pieces come from Sarawak, Borneo, and is available in 1.5" x 1.5" size only and come in card trays with a label.