I came across this HInsdale spoon, and I was hoping to get the forum's expert opinions again. I was able to find information on this silversmith on americansilversmiths.org, and here's the info below. However, I'm not sure about the 3 marks next to his name that make this look a lot like silver-plated. I guess my question is: Is this solid coin silver or silver-plated? Also, what is the significance of the other 3 marks? As always, appreciate any insight you can bring.
The images are below. I have the seller's permission to use these images to ask around a bit. Thank you in advance.
![Image](https://i.ibb.co/cK9gmMp/s-l1601.jpg)