I am pretty sure that the colour is a standard colour. Of course "who's" standard colour is the question. But go see some of the local boat paint
guy's in Nelson and see if they can help with a colour match. Norski over here in Blenheim also make the stuff and maybe able to help.
If you mix a tint into the gelcoat base yourself, the important rule
is, a little goes a long way. Just use a drop at a time. It is also a little unlike paint
. When paint dries, the colour changes slightly, often getting just a touch darker. That's the solvent evaporating out. Gelcoat does not have a solvent that evaporates, so the colour is pretty much the same wet and dry.