Cleaning Prooflike Gold Coin With Ultrasonic Cleaner

Hello all,

I am new here, just wanted to say hi. Also, I have a question regarding a proof like 1oz gold coin that I bought online. There is nothing wrong with the coin per se, but when I look at it carefully there's something red on the surface of the coin. It looks like someone's finger has a bit of red marker and touching the coin, or red lint from the display box that it came in. I'm not sure, I'm just trying to describe what it looks like to me. And it's barely noticeable, but since I'm a perfectionist I want it to look prestine.

So I have been looking into how to clean coins, and I found out about ultrasonic cleaner that won't damage the coin. Hopefully putting my new gold coin in the cleaner with distill water will remove the tiny red marks on them. I will try to do it over time until it's gone, I just want to know what your opinions are. Should I try to remove the red thing using an ultrasonic cleaner? Since my gold coin is proof like and not the older coins. And I did bring my gold coin to a gold shop to check it's authenticity. They put it in a little machine with a soft brush or something to check, and it was authentic. Looking forward to hear everyone's advice! Thanks in advance and cheers!