On Sun, May 16, 2021 at 1:58 PM Erik Levin via groups.io  wrote:

>
> The surface gauge looks to have an interesting surface treatment. Jeweled?
>
>
Commonly called Engine Turning.  See more here

https://www.cnccookbook.com/guilloche-rose-engines-jeweling-engine-turning-
artistic-machining/
-- 
Kirk Eppler, in Half Moon Bay, CA, slowly getting up to work speed for
today.