Oxidizing gold

Hello! I’m not sure “oxidizing” is the right term, but I have a
Byzantine chain bracelet I’ve made for a gentleman who would like it
oxidized, similar to one I made for him in silver. The links are
16g gold-filled jumprings. Is there a product or method similar to
liver of sulfur that can be used safely on gold-filled jewelry?

Thanks very much for your help.
-PJ Wolff