This holographic nailpolish by Gosh is said to be sold out.. Perhaps you might still run into it, because I had been walking past it for years thinking it was just a silver nailpolish, until I saw it swatched somewhere! I was just in time to buy the last bottle before they stopped restocking on it. It is a plain silver based holo so luckily you can find a lot of dupes.
For fellow Belgian nailpolish lovers: try Instant Spa! I have seen some pretty holographic polishes from the designer series sold there.
I will be back as soon as possible with other stuff than nailpolish, but I need to reinstall my image editing program first, so I am digging in my archive at the moment :)
Thanks for reading!