there isn't enough information to know which direction to research plus no photo to go by - all I can offer you is the following: C in a circle is a usual the symbol for - copyright The letters EH will be the maker - have no idea which maker though - as no photo of mark; any information on the style, age, design would help here. Alternatively you might consider having the piece appraised on line if not set with precious gemstones. High quality Gemstone jewelry should be appraised in-store. But Note - Not all jewelers are qualified to identify gemstones.
