Costus Absolute Oil After a lot of extensive searching, we have added Costus absolute oil to our collection of pure floral absolute oils. It is an (in most cases) yellow-colored liquid that is extracted from the roots of Saussurea costus. A highly prized ingredient in the perfume industry, it smells musky, woody, and somewhat similar to Sandalwood. After all, it is a root-based aroma. When you first smell it, you will be surprised to also experience some floral notes that add to the complexity of the aroma. Aromachology offers a very high quality costus absolute oil that is one of the best available out there at very competitive price.