Look in the yellow pages for an antique dealer, There are usually a lot around. Tell them you don't want to sell it, they'll hit you with a low figure if they think you want to sell. You just want an appraisal.
I Have A International Silver Company Water Pitcher And It Looks Antique. Where Can I Go To Find Out It's Value?
You can try with magnifying glass-if your tray is plated of pure silver and nickel silver is visibly different.
Plating must be worn-out on some places! If you want to be sure you can
test it with nitric acid-put just one drop on back of your tray-green
colour= copper,brass or nickel silver.Cream colour=silver or silver
alloy. Rinse it well!Good luck!