Search for the mark stamped on your porcelain article by using an alphabetic index if you know the company that manufactured it or the country it belongs to, by using a date index if you know the period in which it was made, or by using a sight index that identifies the shape of the mark. You can also try keywords if you are using an online guide, or check cross-references if using a book.
Start by identifying the letters or words in the mark. They give information about the manufacturer or the country the porcelain was made in. If they are legible, use them to locate your mark. Identify the the shape of the mark, which might take the form of an anchor, circle or shield, and use it to search.
Suppose your porcelain has a stamp that has the picture of a snake with the word Belleek above it and Willets below it. If your guide is a book, search for Belleek or Willets in the alphabetical index, turn to those pages, and locate your mark. Search for "snake" in the sight index, and find your mark. If using an online guide, either search in the Words & Initials category, or directly type the keyword "Willets" or "Belleek" in the Search box. You can also click on the category Animals, Fish & Insects and search through the list of images.