Reference 510.513 is the Lemania 5100 powered Cortina, with the blue dial, but yours is different in a couple of respects. It does not say Cortina and it is black-on-black. I wonder whether this one is a 510.501 dial, transplanted into a Cortina case? Or perhaps there was a "no name" Cortina, like the "no name" 5100 powered Silverstone? Let me check the files, later today.

Here is the Gallery of Cortinas, and the Reference 510.513 Cortina . . .

And here is the Reference 510.501 . . .

And here is the watch that you showed . . .

Some further research will be required.

Jeff