Best way to make an image of a shiny proof-like printing plate

Today I was in a bank archive, looking at an old printing plate. 

We want to scan it and photograph it. The issue is that it is very shiny, like a proof coin and reflects like a mirror.

We are using a Nikon digital camera, shooting in camera raw format. 
I also used a cameraphone for comparison.

Today was just a recon op - 2 hours to test out feasibility of techniques. No problem with capturing detail in the images, just a serious reflection of the photographer and the background on the subject plate, and some glare from lighting.

Will this work better with a scanner - I bought a 600dpi flatbed which I will strip down so that the plates will sit directly on the glass. Scanner tests with a proof coin were satisfactory.

Scans of shiny metal objects are different to photographs - ideally,  I would like to get both to work.

Thoughts and suggestions are welcome.

With a camera at a slight angle and dark surroundings or from the top down through a hole in a dark surface would be my suggestion.

Take a piece of paper/cardboard, paint it black and cut out a hole for the camera lens. Then, photograph through the cut-out at a slight angle, so instead of reflecting the camera lens, it reflects the black.

Avoid direct lighting, as it will produce more defined shadows and reflections. If you can, get a diffused lighting lamp.

Thanks for those suggestions :)