Instructions
Look for the original store tag. A number of collectors have uncovered foreign pieces that still have their original price tag attached, which can tell you what it originally sold for as well its age.
Turn the piece over to examine the bottom for a paper label. Because paper labels are no longer used, they're great signs that the piece is older.
Check the bottom of the piece for a foil label. Although foil labels are more recent than paper labels, they also are no longer used.
Rub the printed mark on the bottom of the piece with rubbing alcohol or nail polish remover. Modern rubber stamps use an ink that will wipe off, while older marks will stay in place.
Read the label carefully to see if you can identify when the item was made, even as a rough time frame. For example, an "Occupied Japan" label means the piece was made during the US occupation of the country after World War II.
Buy pieces that are marked, regardless of their age. Unmarked pieces are often considered worthless on the secondary market.