I like the color, but I'm just confused. I wouldn't consider that to be Cobalt blue. It looks like the deep navy used in GMK Rudy to me. When I hear cobalt I think of a brighter, more vibrant color. Maybe this is a deep cobalt? Also confusing because there is a GMK Cobalt but this has nothing to do with it.
That's how RAL named the color I'm using, so I just went with it, thought a gem theme would be nice so "cobalt" fitted pretty well into it

If you google "cobalt blue" you can find a bit of every tone of blue tbh.
Rudy's blue uses RAL 5003, which is indeed pretty close to the RAL 5013 I'm using, just a smidge lighter/less saturated (well, depending on how the designer color-matched it there could be a bigger difference, unfortunately I don't have it to compare).