Hibernia - hallmarked in Ireland The Dublin Assay Office was established in 1637 to supervise   the assaying of all gold and silver in Ireland. Located in Dublin   Castle, the office serves as a consumer protection agency,   and the hallmarks given are accepted worldwide. All Celtic fine jewelry from Celtic By Design bears these hallmarks as your assurance of quality and authenticity.
The Hibernia is the official mark of the Dublin Assay Office.  This mark features the profile view of a woman (Hibernia) in olden dress, together with a harp (the national symbol of Ireland).  All jewelry receives this mark in the form of a stamp, with the exception of very delicate pieces.  For those, laser marking is sometimes used, or the hallmarking stamps may not be used at all.

This mark has changed over the years, but the Hibernia is the current standard of all pieces hallmarked in Ireland today.

Additionally, the grade of metal is stamped on the piece.  So 0.925 sterling silver would receive a hallmark that looks like this:
 Irish Hallmark For Sterling Silver
Where “925” indicates the purity in parts per thousand (i.e. 92.5% pure sterling silver).    Gold would receive one of the following hallmarks depending on the karatage of the piece:
 Gold Irish Hallmarks


Where, for example, the “10” indicates 10K and the purity is 417 parts per thousand, etc.
Other marks may also appear on the piece, such as the maker’s mark, a fineness mark, or a letter indicating the year in which a piece was hallmarked.  The letter cycle assigns a new letter each year, but inclusion is optional.
Items are generally sent to be hallmarked before their final polishing.  This is done to protect each piece from the marking process itself.  This can sometimes make hallmarks slightly difficult to read depending on the amount of final polish needed.
Should any item fail the purity requirements for hallmarking, the piece is either hallmarked at the next lower grade or is returned to the manufacturer with no hallmark for recycling.