What are the grades of agarwood origin?

The origin of agarwood ranks first: Hainan agarwood ranks first, followed by Vietnam, Thailand, India, Cambodia and Malaysia. The lower producing areas are Indonesia and Papua New Guinea. Generally speaking, the grade of agarwood is divided according to the origin, aroma and resin content; The aroma of the same agarwood produced in different places is often very different (Hong Kong's agarwood is the best proof, covering almost all the agarwood varieties in the world); Whether this phenomenon is related to related microorganisms and environmental factors deserves further discussion. Classification by specific gravity: submersible is the best, followed by semi-submersible and semi-buoyant, and the worst floating on the water surface is basically oil. The traditional classification method is often determined by the proportion of products and water from the same origin: if it is fragrant, the resin content exceeds 25%; The fat content is gradually decreasing. And yellow is ripe and fragrant; The specific gravity of agarwood logs is about 0.4; In Korea and Japan, agarwood with resin content over 25% can be used as medicine; In China, it should be above 15%. By color, the first grade is dark green, the second grade is brownish green, the third grade is golden yellow, and the fourth grade is yellow. There is almost no fragrance before burning agarwood. The higher the resin concentration, the more mellow and mild the fragrance is when burning, and there is no pungent or bitter taste. It is speculated that the reason is that the original plant fiber and other substances that can be converted into spicy and bitter taste are reduced or disappeared during combustion. On the grades of agarwood. According to the Dictionary of Traditional Chinese Medicine and Japanese classification method, green and purple Daphne are the highest. But in many ancient books, there is no mention of the existence of purple incense.