Seiko

Hoping to pick some brains! On a whim I acquired this, I believe a 5722B from 1965. My first GS (been eyeing up a Spring Drive for a little while and saw this whilst browsing).
I’ve seen a couple of these with a black dial but they seem to be almost universally white. I’m wondering if this black dial might not be original, despite what appear to be correct markings at 6 O’Clock.
Whether all original or not, I’m really impressed. Love the classic clean elegant lines of this piece and definitely not my last GS.
Many thanks 🙏🏼

the markings in Japanese on the the back say basically, 

Very interesting indeed! I didn’t realise it wasn’t just “normal” for that case back.

The 57GS did not come with black dials, only the typical silver dials. Many of the GS medallions were also 14k gold, so I am unsure as to why the medallion is that dirty. The W Seiko crown is also suspect, it looks like the text is pushed up to the end of the crown and slightly cut off, which makes me think it may be an aftermarket replacement.
Would be nice to check out the movement to make sure it's the correct 5722B movement. Case has been polished quite a bit but that's the least of your worries, personally if I was you I would try to send it back and get a refund.
Best of luck.

I’m going to remove the case back to ensure the movement is genuine. I quite like the black dial (or would not have bought it!) and given the price I paid I wasn’t expecting it to be 100% original.

Medallion looks like that because it will almost certainly be plated tin. I tested one of these once with a heat gun. Melted away in seconds (tin melting point is under 300 degrees Celsius. 14K gold, which is indeed what the vintage medallions are made from, melts at closer to 900 degrees).
If anyone wants a black dial 57GS, your best option would be to settle for the reissue SBGV011.