Kintsugi is a Japanese technique for repairing broken pottery with seams of gold. The word means "golden joinery" in Japanese. This repair work was done using a lacquer or resin that was sprinkled with powered gold. (The process is also known as kintsukuroi, which means "golden repair.")
The most common history I've found for this practice dates to the 15th century when a shogun needed a broken bowl repaired. Over time, these repaired pottery pieces became so prized that people would intentionally break items in order to have them repaired this way.
The Japanese have several related techniques for repairing broken ceramics that involve other metals—including silver, copper, or bronze—or include pieces of other ceramics to fill missing gaps. Each of these produces objects that are not just repaired, but that have become works of art. The broken places are highlighted in ways that bring greater beauty to the piece than would be possible without the break.
The traditional kintsugi technique involves using urushi lacquer and real powdered gold to make the repair. Urushi lacquer is made from a plant related to poison ivy, so it causes reactions in many people while performing these repairs (although it is no longer reactive after it dries in the finished object). This toxicity also makes the lacquer itself expensive in addition to the high cost of real gold powder.
These two factors, along with the amount of practice it takes to become proficient in this repair technique, means that there are a limited number of craftspeople who still offer traditional kintsugi work. There are, however, many artists (including myself) who are using modern materials to create similar effects much more inexpensively, making this work available to a wider range of people.
I have collected a number of images of kintsugi work (both traditional and modern) on my Kintsugi board and my Kintsugi stone jewelry board on Pinterest. I have also collected a number of resources, including information, studios, artists, supplies, and classes for both traditional kintsugi and modern methods in the Kintsugi Resources section.