How do I get the tarnish off of this gold filled watch chain/fob.

Gold does not tarnish. It is the silver or copper component. Polish like you would sterling.

 

I would use a Sunshine cloth or something similar.

I saw the other day that they now have a "gentler" cloth that is supposedly less abrasive & they say is better for fine jewelry. It comes in a light blue colored cloth. I would imagine it would be good for the plated items because you are basically dealing with a thin layer of silver.

Has anyone tried one of them?

 

I am with @bercrystal . Sunshine cloth.

 

eBay usually has a great variety of them to buy & some sellers lot them in group of 5, 10+ & they are cheaper that way.

 

https://sunshinepolishingcloth.com/just_one-blue.html
Is this a normal price? The size seems rather small?

 

That's about right.

 

OK, I hope no one yells at me, but I have found that plain, white toothpaste polishes gold. I would use some with a soft toothbrush and then rinse.

Should I duck????

 

It depends on which type of toothpaste you use,some are very abrasive................ https://www.sheltondentistry.com/patient-information/toothpaste-abrasivity/

 

I'm going to duck even lower than Marie as anything I'm really struggling with I dunk in white vinegar BUT I've not tried it with gold plated and ALWAYS test patch first as if there are areas with complete plate loss those can go black. It's brilliant on old brass chains and findings on the deco necklaces I seem to have a lot of (how does that happen? Is there a breeding program?). Never dunk anything with foil backed gemstones as it's gets behind them and darkens them and I wouldn't use on anything precious. Enough disclaimers I hope!
Edit- I watch it like a hawk and pull it out as soon as I see it brighten which is usually 30 secs to a couple of minutes. Removes verdigris brilliantly too.

 

This brass metal necklace had about 30secs in vinegar. The after photo isn't very clear but you can see how filthy it was before.
As I say though I do not know if it would damage gold plated stuff.

 

I’ve used this formula with good results (found it here
https://chatsworthlady.com/2018/06/03/snakes-on-a-chain-mystery-jewelry-maker/)

1 pint warm water
1 cup white vinegar
1 tablespoon of sea salt (Kosher salt may work also)
1 teaspoon liquid detergent (dishwashing or laundry)

Mix thoroughly and soak item for at least 15 minutes, then brush off gunk with a throwaway/cheap toothbrush. Use a second soak/brushing if needed. Rinse thoroughly and dry with paper towels. Polish with a gentle non-abrasive silver cleaner such as Blitz Silver Shine, (see link below). Dip/rinse in water with a drop of detergent added. Rinse with clean water. Dry with a clean cloth and leave item to completely air dry (in a warm place/sunshine is ideal) for at least 24 hours.

 

Long story short I was advised not to use vinegar because of the supposed enamel paint on the sequins which were rigid and thought to be metal. I gave it a gentle wash in plain water and they dissolved into a gluey mess!. Turns out they were probably gelatin which I didn't know existed until then.... Turns out it was much more beautiful without them so a blessing in disguise.
After I killed the sequins I used a vinegar bath and it worked beautifull to clean the metal.

 

You are very welcome, @Bookahtoo