Hello, this is Fountain Pen Research.
This is the color difference between PEEK black vs conventional black resin (general-purpose plastic such as PP, acrylic (plexiglass), ABS, PC, etc.).
Unlike the black color of regular pastics that usually comes to mind when thinking of black,
I found that the PEEK black was different.
I didn't notice when it was in rod form (unmachined).
As I machined the material the differences began to emerge.
So this is what I discovered after machining.
The photo below is a side by side photo of the typical black fountain pen resin and PEEK Black.
It feels so different that it cannot be called the same "black".
My guess is that graphite may have been added to Black Peak, but this is just my guess.
It has a silvery black color.
One thing is certain: the PEEK plastic (tan, black, blue, green) all have a slightly silvery feel regardless of color. So it may not be the graphite.