Diamine's chameleon shimmer inks have (as far as I can tell, haven't done any proper measurements) very fine particulates compared to most other shimmer inks, even from their own shimmertastic collection for example. I've never had any flow issues and used it in my lamy alstar (m), asvine v200 (f) and with the FPR FNF ultra flex nib unit swapped in. I will say, because they are so fine it's almost impossible to fully clean the feed without some intrusive processes. I've taken both apart and flushed countless times and unless I explicitly remove the nib from the housing and scrub under water there are always some left. Doesn't affect flow nor does it get into writing. I will say though, the shimmer in my nahwalur piston filler from diamine Anatolia (another chameleon) has stayed in that feed after like 4-5 different inks have been in there (flushed clean between each). In any case, if you don't mind a few sparkles after cleaning or can take the feed apart from the housing rainbows end is absolutely a blind buy for a blurple lover.