How might I clean this brass (?) plate?

[Balsamicpearls]

I've inherited this decorative plate. I think it's brass but not sure. I know the colours of the peacock would be lovely if cleaned up but not sure what to use. Any ideas please? Thanks

Brass polish. You can still get it in hardware shops.i spent a lot of my teen years polishing my mum's brass collection dustcollectors

Thanks. Do you know how I'd know if it is definitely brass? Can't see markings or anything. I suppose I will just test it on back anyway

Is it brass? Looks more like copper in the photo.
Before you try any polish or other chemical cleaners, I'd start by giving a wash, with warm water and mild detergent and a soft brush or sponge, nothing harsh. Start on the reverse or a small inconspicuous area first.
Have a look at your local auctioneers websites for free valuation session and ask the metals expert for the best method of cleaning it, without damaging it or lowering it's value.

Oops, should have proofread before posting. After washing, rinse with clean water and dry with a soft cloth.

Thanks for the good advice