The idea here was to have a necklace that could display the month and date along a line representing the hexadecimal system 0 thru F (which is 15). You'd need some way to show the difference between month and date, and some way to put in 2 bits of information for the date, since the highest one bit can show is 15 and you need to go at least as high as 31. Incidentally, this layout has some significance to the colors, but they're not the primary thing. The pale beads at start and end correspond to 0 and 13-15, all numbers that don't get used in the 12 month year. The black beads are winter months, light ones are spring, green for summer, and red/brown for fall. Get it? It's just a little bit of metadata, not crucial to the functioning which is all about position.