All genuine Waterford crystal made since 1947 features some form of authenticity mark. Pieces made between 1947 and 1999 have the word 'Waterford' etched into the bottom. Pieces made since 1999 have Waterford Crystal's seahorse emblem etched into the bottom.
The authenticity marking on pieces of Waterford crystal changed from the word 'Waterford' to a seahorse etching at the turn of the millennium as part of Waterford crystal's millennium series. Other ways to determine whether or not a piece is genuine Waterford crystal include checking for a gold label with the seahorse emblem, examining the thickness of the item and holding the piece up to light to check for a prism effect.