Tell them it's unicorn horn and that's just one of the color phases.
LOL, yeah, I'd forgotten about the colour phases
(that's in TBB IV isn't it? ) That'd work...
I posted a question on the Official NFAS FB page only to be told Horn only.
I was then set upon by mocking idiots one of whom thought Deer shed their "horns" every year not realising that antler and horn are different materials..... so bone and antler are "not allowed" Sheesh and people wonder why I tend to shun the archery societies and competitions!
For completeness it was apparently the EWBS who allowed the use of non animal materials.
Del