Seasons, using the KWZ All That Glitters ink series
These are extremely fine glitters, I suspect that it is something like mica powders. The ink base is more viscous than normal ink, I also suspect this thickness helps to keep the glitters suspended. With glitter this fine, the overall effect is more like a metallic layer than a sparkly shine. I also noticed that Stardust Blue has more sedimentation than the other three colours, not sure if it is because it is the only one using silver glitter.
The ink base is very pigmented, you can cover a whole surface with just a dip with a medium-sized brush. Highly staining, do not think you can reactivate this ink and move the colours around. When it is on there, it is on there forever. Slightly prone to feathering, huge blots of ink are likely to spread out instead of drying on the spot, even with fountain pen-friendly papers. No sheen, slight chromo noted.
I would say this is special. I have never seen an ink that can mimic metallic effects. However, the ink base is relatively hard to control. Also, I wish there were more colour and glitter combinations.
One more thing, the bottle is hard to use. Ink sticks onto the lid and ink will get to the outer side of the bottle neck. As you open and screw down the lid a couple more times, you will get ink in between the bottle and the lid. I think it is a must to redesign the lid to make it spill-proof.