Titanium-coated Druzy Jewelry Care

I give a recipe for the homemade jewelry cleaner to my customers:
about one tablespoonful of Arm & Hammer Washing Soda dissolved in a
cup of very warm water–throw in the jewelry and a small piece of
aluminum foil. Does anyone know if this is safe for titanium-coated
druzy. Does the coating require special care?

J. S. Ellington
jsellington@cs.com