Amber is considered semi-precious because it is not considered an entirely precious gem. This type of rock contains transparent organic matter from the sap of ancient trees, and its ages range from 30 to 90 million years. It is usually orange, yellow, white, reddish brown, etc. The characteristic of amber stone is that it often contains creatures such as mosquitoes, insects, leaves, etc., that stick to the tree sap and will gradually fossilize over a long period.