As for the center caps, I had them colour coded to the same colour as the wheels. The wheels were powder coated but the caps had to be spray painted for obvious reasons however the colour match is exceptional. For the emblems, the chrome on mine was in really good condition, so when you take the wheels off you can pop out the center caps, at which point the Mazda emblem in the middle is held in with 4 push fit tabs… Very carefully push them and the whole badge will separate from the center cap.
After that, take the wheels and caps to your place of choice, choose your colour and you should be good go. There may be an extra charge for the center caps as they can’t be painted at the same time as the wheels (plastic), but whoever does the work should be able to sort that out.
Keep the emblems and give them a really good clean up, I find methylated spirit is really good for this. If the chrome is shot, you can buy chrome spray paint which does a pretty good job in my experience, or silver if you prefer.
Then just refit them to the caps when you get the wheels back and you’re good to go!
While the wheels are off, if you’re able to, give the calipers a fresh coat of E-Tech red caliper paint (have a look on ebay) - it’ll look a million dollars/quids
Sorry for late reply but I’ve only just seen your original post. I had mine powder coated black so here’s a picture. I ummed and aahhed a lot about doing them anthracite but eventually went for black and I like it. Regards centre caps, I found some black ones on eBay that were a perfect fit. Hope this helps