15 pink 255 51 153 1
16 copper 255 186 38 0
17 skin 242 204 204 1
18 light_orange 255 230 76 1
19 brown 102 51 0 1
20 blood 166 5 36 1
21 juryo 237 191 166 0
22 aurora 245 227 247 0
23 hold 217 71 0 1
24 hold_active 224 133 82 1
25 fracture 128 128 255 1
26 acid 178 255 26 0
27 amethyst 255 51 242 0
28 aqua 0 128 255 0
29 bronze 204 102 51 0

I don't think it's alpha, it looks like any colour that can be equipped is a 0 and any that can't is 1

I still find it kind of odd