We all have a few pieces of Grandmother's china, or maybe just some plates we've had forever yet don't know who--or where--they came from. Find out if those odd pieces are worth something and pare down your "keepsakes" to a few real meaningful pieces by doing some research to find out what they're worth. Digging up some information about those plates will prepare you to consult---and bargain with---antique dealers if you decide to sell them.
Inspect your plate. Manufacturing imperfections are not necessarily a drawback, but cracks and "crazing"---the crackling of a finish as it ages---are. Note the pattern and its themes; try to determine if it was printed, painted or some combination thereof. Stamped patterns were not very common until midway through the 19th century, when machinery was perfected that could be used on porcelain. Measure the plate and make notes of any imperfections. Photograph the plate, front and back, using a digital camera.
Turn the plate over and look for a maker's mark. These are impressions, printed stamps or signatures put on the plate before glazing. A maker's mark will identify the company that made the plate, and perhaps the name of the pattern on the plate, or even the designer of the pattern. Other information included on a mark might be the date it was made, the series of dishes to which it belongs, or even its production run. A good photo or reproduction of the maker's mark will allow you leave the plate at home when you go to the library or an appraiser.
Check online to find the name of the maker, pattern or specific mark---whatever you find. A website like Replacements, Ltd. (see Resources) is a good place to start, because it has pictures of many patterns. If your piece is in stock, they will also quote a price for the piece, and your search will be nearly done. If you have the name of a maker or a designer, search out a collector's club that has a history page. The plate shown here has a clearly printed name, a not-so-clear company name ending in "ley" and a pattern name. Searching with these names turned up a number of interest groups; the Australasian Shelley Collectors Club's history page told us that Shelley was the descendant of Foley Potteries, owned by J.F. Wileman in Staffordshire, England (1869 to 1892). Foley Pottery was absorbed into Wileman & Co. in 1900, which became part of Shelley Potteries in 1925. So our stamp places our plate in a period from 1869 to 1892.
Find a source that will provide more specific information---pictures will provide documentation. Our plate wasn't shown anywhere, but both the Australasian Shelley Collectors Club and Ruby Lane, an online antiques dealer, had pictures of a very similar plate made by the same maker with the same technique: hand-tinted transfer in a style called "Victorian Aesthetic," dated 1879. Dozens of similar patterns can be found on Staffordshire china of the period. Prices quoted for similar plates in good-to-excellent condition run from £39 to £97 on several antique dealers' websites.
Consult an appraiser. Now that you know what you have---how old it is and where it came from---find at least two experts who can judge the condition and quality of your piece dispassionately. Perhaps your plate is destined for the heirloom shelf, but it might also be an investment for your child's college fund!
Antiques aren't only appraised according to age and condition. Tthere has to be a market--people who want to buy them. An appraiser can tell you what your piece is worth and what you can probably get for it. Check an appraiser's credentials before trusting his estimate. He should be an associate member or accredited appraiser in the Appraisers National Association. An accredited appraiser will have passed a course in Uniform Standards of Professional Appraisal Practice (USPAP) offered by the College for Appraisers or another accredited institution. If you decide to keep your antique china, add it to your insurance inventory along with the documentation you've developed.
Most people are emotionally attached to family heirlooms or have been given a story about a piece that might be more imagination than fact. Be prepared for a realistic opinion.