Agarwood (or “Agar”) is the dark resinous heartwood that is formed in Aquilaria trees when they become infected with Aspergillus sp. and Fusarium sp. The resin this forms produces the fragrant substance. The more resin the wood contains the more aromatic the fragrance and the heavier the wood becomes. Excellent agar wood will not float and for that reason the Japanese call it jinkoh, the sinking wood.

The most expensive and desirable agar wood is wood that has been covered by plants and soil for decades, perhaps hundred of years. The pressure compresses the resin and makes it very dense and compact. These old, partially fossilized pieces of wood are the purest form of incense to the Japanese and as such command quite a high price.

In its original state the wood is light grey. Only after exposure to the fungus does it become dark and resinous. Unfortunately, unscrupulous dealers will often dye less expensive wood to make it resemble infected agar wood. If you are really interested in the balsamic, ambergris, woody and deep fragrance of this wood find a reputable traditional incense maker.

Also, the quality of the fragrance can be divided into six traditional categories named for traditional groups or communities in Japanese society. They are:

Kyara – A dignified, gentle fragrance with a slightly bitter note. It smells like an elegant and graceful aristocrat.

Rakoku – Which is a biting, tangy fragrance that is reminiscient of sandalwood. It is somewhat bitter and is said to remind one of a warrior.

Manaka – A bright, tempting fragrance that is changeable and it is said like the emotions of a beautiful woman.

Sasora – Cool and slightly sour, it can sometimes be mistaken for Kyara. Especially when the wood first heats up. Very often the scent is light and almost beneath notice. It is said to remind one of the fragrance of a monk.

Manabau – Usually sweet, but sometimes coarse and unrefined in aspect and for this reason it is the scent of a farmer.

Sumotara – With its sour fragrance at the beginning and the end of the scent it can very easily be mistaken for Kyara. Ocassionaly the fragrance has an uncouth and perhaps offensive character. For this reason it is said to remind one of the scent of a servant who pretends to be an aristocrat.

You should burn agar in small slivers on a mica plate to enjoy the deeply relaxing and mysterious scent. In fact, a 1993 study by Japanese scientists concluded that that its effects were like a strong sedative and that it extended sleep periods.