Pilot Iroshizuku Ama-iro is a vivid sky blue with a touch of red sheen and a little shading.
Scans
While the large swatches trend a little darker, the writing is a very pleasant sky blue on each paper. It’s not too light or pastel, even where there is less ink from shading.
Photos
There isn’t a lot of sheen, but it is noticeable in the large swatches. In writing when it does show it mostly gives the letters a tiny bit of an outline.
Microscope
Under the microscope, it’s bright and even. You can see a little bit of the shading along the edges of lines and in the larger swatches it’s more visible in foreground fibers where the ink is heavier.
Chromatography

The chromatography starts light blue then gets even lighter and splits oddly toward the end, clinging to the edges and extending rather than from the center.

Under UV light the empty area in the split at the end glows blue slightly, and there is a blue halo at the edge. The swatches didn’t glow in UV, however.
Verdict
Iroshizuku inks are not always the most complex, but they are exceptionally reliable. This ink is no different. It was one of the first inks I bought when I started back into using fountain pens, and I’ve used it constantly over the last few years and it has never let me down. I always keep it in at least one pen. I actually had it in a TWSBI Diamond 580ALR for over two years testing how well the seal would keep with occasional use, until I wrote it empty.
Questions or comments? Contact me on Mastodon