Tea Service with Crown G S X

I have a complete tea set which I am going to part with however I wanted to know if you could help me know more about it. I’ve had it aprox. 30 years but I don’t know where my Mom got it from. I cannot get a good picture of the stamp but it has a Crown then it appears to be a G S X (each in a square box). Can you help identify this for me? Is this something a collector would be interested in? Thank you.

I think the X might be crossed keys.
Check out the silverplate mark for the Goldfeder Silver Company here:
925-1000.com/silverplate_G.html

Thank you. You were correct, the “X” is a set of keys crossed. I found the exact stamp on the website you suggested. Thank you.

Rose