Master's knots are identified by color. But, there are only so many colors that are easily identifiable to the general populace. There is a small decorative distinction.
Alderly - the main knot is centered between two beads - or smaller knots.
Jira - suspended down off the neck cord
Lightning Sea - a forged silver lightning decorative necklace
Mal'Covia - the knot itself is surrounded by a stone ring
Tivalera - centered in the middle of a 3 to 4 inch beam
Xinji - two bar-shaped beads set to either side of the knot
Unlit Lands - two skull beads on either side of the knot
Eldland - un-adorned
Xinji's beading tradition often sets multiple beads on the necklace. These extras are reflection of their master, and their master's master, etc. Considering that their masters are grouped by Wood, Fire, Water, Metal, and Earth - you often see the same beads in different patterns suggesting different times and people depending on their order and the age that you became Master.