Ever since I had the chance to use Cobalt Blue Dark (PB 74) from the Kremer Pigments Set 1, I've been hooked on that colour ever since. That's one of the most granulating paint I've ever seen.
I only have one full pan of Cobalt Blue Dark from the Kremer Pigments set so I'm very precious with it. I wanted to get more but it's not easy nor cheap to just buy the paint straight from Kremer Pigments have have it ship to Singapore. So I bought other versions of PB74 to see if they have the same look.
The swatches above were painted on Daler Rowney Aquafine coldpress watercolour paper.
These were painted on Arches coldpress paper.
As you can see, the other brands look different.
Paintings painted with Kremer's Cobalt Blue Deep is quite distinctive. This blue is darker than French Ultramarine and can mix with Burnt Sienna into a dark gray or black easily.
I can recognise all the sketches that I've painted with Cobalt Blue Dark easily.
If you also use Cobalt Blue Deep or PB74 and it looks anything like Kremer Pigment's version, do let me know the brand you have. I'm thinking of switching my use of French Ultramarine with this colour exclusively.