I'm not expert on this type of thing, but I like to think I have enough experience to spot a fantasy or fake piece.
My last question is; What metal is it? It looks like the patina that aged silver would go! (Good sign)
Everything I'm about to say is speculation & I'm really keen for those with the right books to chime in, but...
Assuming it's silver, it must have belonged to one of the Officers of the Jamaican Militia & not an enlisted man. Which leads me to my speculation; I wonder if it's a one-off commissioned piece paid for by an Officer??
I wait with interest for the right attribution, but you do need to answer the questions, so others can be sure of the ID.
Assuming it's real, I'm pretty sure it's a $1000+ piece.