German gold cross marked 20 original?

[ckckck34]

As above was left to me by my grandad I'm 99% sure it's original marked 20 under pin.. would any member be kind enough to confirm this and a rough value thanks

[JSlisset]

Although it is dificult to see fine detail owing to size of photos it does appear to be correct. I have one of these "20's" as well made by Zimmermann.