Cloisonné is a form of enamelware where the enamel paste is contained within compartments or "cloisons" of wire. Often of silver or gold, the wires remain visible on the finished article, threading between areas of colour. As of 2010, there is a great deal of mass-produced Chinese and Middle Eastern cloisonné on the market in the shape of bowls, plates and incense burners, but the interest of collectors focuses on the sophisticated wares that emerged from Japan from 1890 to 1920.
Turn the item upside down and check the base, especially the rim. Does it look metallic? Give it a tap and listen for a clinking sound. Cloisonné is applied to metal bodies, usually of copper. If your item is made of pottery or wood, then it's definitely not a piece of cloisonné.
Inspect the design itself. Shapes and details should be demarcated with a pattern of wires -- chunky and easy to spot on lesser pieces, extremely fine on the best wares. Once-bright silver wires go dull over time, so look carefully. If you're item has passed Steps 1 and 2, then it's almost certainly a piece of cloisonné. Steps 3 and 4 will help you to assess its quality and place of origin.
Take a step back and consider the design from an aesthetic standpoint. Is it a series of abstract patterns, perhaps with some stylised flowers? If so, then the piece is most likely of Chinese or Middle Eastern origin. Or does it portray a naturalistic scene, perhaps a bird such as a wren or sparrow perched on a twig and surrounded with a spray of flowers? If this is what you see, then you're holding a piece of Japanese cloisonné.
Examine some of the individual cloisons. Rather than being uniform blobs of colour, cloisons on the finest Japanese wares often display delicate shading.
The Japanese also perfected a form of enamelling known as "wireless cloisonné," typically used on pin trays and the lids of trinket boxes. To identify it, follow the steps above but on this occasion don't expect to see any visible wires in Step 2. Wireless cloisonné is well worth looking out for, as it's extremely collectable.
Cloisonné is extremely delicate and impossible to restore, so any kind of damage will put a big dent in the value. Don't even think about polishing those dull silver wires!