The term 'JEWELER's GADGET' is a crossword solution that can be broken down into two words: 'Sizer' (5 letters) and 'GADGET'. Sizer is a tool used by jewelers to measure the size of a gemstone or other jewelry item. It is usually made of metal and has a variety of different sized slots that can be used to measure the size of a stone. The GADGET part of the term refers to any other tool or device that a JEWELER might use in their work, such as a polishing cloth, tweezers, or a magnifying glass. Jewelers use these tools to create and repair jewelry pieces, and they are essential for any professional JEWELER.