Quote Originally Posted by davidlpope View Post
The complicated bit is that a certain shade of blue ("azure") signifies a "different" color, rather than being lumped in with other "blues".

Consider the thread count for the Carolina tartan:

R64A28K32Y6K8W8K8R2G56R26K8R8W4

where the "Carolina Blue" color is listed as "A", azure.
Tis true there are exceptions to almost any rule but the general idea is that tartans are simply defined by the arrangement of generic colours in a particular pattern.

It is up to the weaver and/or the customer to determine the actual shades used and why.