If you look at the image above, you can see the grain range of each grade, from non-curly (1A grade) on the left to super curly (5A grade) on the right.

We learned from the maple, spruce, and cedar markets and adopted this method to have a base grading system when selling core in the market.

My father, Joma Winkler, used to use a wood scoring method adapted from NHLA scoring rules, but that method didn't work for me when talking to luthiers.

It's not perfect, but I've found this to be very helpful in understanding what customers expect.

Koa is usually graded based on grain strength, depth, curliness (tiger's eye or curly pattern), or appearance of the grain, with the more decorative the wood, the higher the grade.
All grading is done using a special machine.
Color is not a grading factor; each tree's core can be honey-colored, brown, dark brown, or reddish-brown.

We will do our best to supply what matches your demand.