Here's some finish testing.
In the photo below from left to right we have:
1) Blue holo flake on black base, needs black tint finish.
2) Black flake under glass and black flake over glass, clear finish. Sparkle go byebye.
3) Black tint on Tas Oak.
4) Black/Blue holo burst trial with clear finish. Feathering the burst will need a super, super fine mesh (flake is 0.08mm).
Here's Blue holo suspended in resin...
Don't look into it for too long or you'll see the creepy screaming face.
...on carbon.