Colors By Llarowe, Black Gold Texas Tea is the darkest strong holo polish I have come across. It's hard to get an actual black holo because of the holographic pigment seems to change the colour to a lighter, grey tone.
The flash made the holo reflect like crazy for the photos making it difficult to see the studs
So I took a photo without the flash:
Colors By Llarowe - Black Gold Texas Tea
4mm Silver Studs - Born Pretty Store