How open up tap to change valve?

Hello,
I've bought some second hand 'vintage' taps for a small hand basin. I've cleaned them up, and now I want to renew the valves before fitting them to the basin. I know the first step is to remove the cap at the top so that I can unscrew the handle. However, the caps don't have any grip around the edge or any obvious place to wedge in a screwdriver to pop them off. So, how do I remove them? You can see the tap in the attached image.
I wanted to get expert advice before I started forcing a screwdriver under the cap as I thought this could damage the cap. Any advice much appreciated!
Thank you.

Use something very thin to prize off the indices.

Done it! Thanks. I just wanted to check that there wasn't a different method in case I messed up the indices, but they came off fine.
Thanks again.