Touching up/painting gold on a headstone

An alternative to DIY - the stone masons that work in the cemetery would likely be able to make quick work of it. As they will be there often enough, they can just add it on to another job, no need for a special call out.

I'd be of the opinion that no off-the-shelf consumer-grade gold product isn't going to last in a graveyard.

That's your best bet, leave it to the pro's. I can't imagine that it will cost much.

(Edit typo: changed "is going to last" to "isn't going to last".)

A quick google threw this up......

Seems you need to use an undercoat with it also, makes sense.

I am a stonemason the bottle above is a good paint to use

Put a yellow undercoat on and then 2 or 3 coats of gold paint

Scrape off the excess with a blade keeping it flat against stone with a sponge and water