The article below is I have to say the best I have read on the role of science in determining the age of Chinese porcelain. I posted another article here (PIXIE Method) a few days ago, you will see this current article dismisses the PIXIE method of testing and gives a good argument why, this current article also explains how a TLC can not really be manipulated by exposure to external radiation sources as I thought and many others still think. Items of pottery or porcelain submitted to external radiation sources give of a distinctively different glow curve compared to a bell weather glow curve given by original pieces.
The Role of Physical Science in the Study of Cultural Heritage
Since the first observation of luminescence emission from a ground-up pottery upon heating by Kennedy and Knopff in 1960, thermoluminescence (TL) testing has found wide applications in the dating of pottery of archaeological interest and the authentication of work of art. Samples must be taken from the object to be tested. The required weight is as little as a few milligrams to preserve the physical integrity of the artifact. The sample is then processed into fine grains. Luminescence is emitted from the fine grain sample on a hot plate when temperature is raised from room temperature to about 500 °C. The plot of luminescence intensity versus temperature (in degree Celsius) is called a TL glow curve. In principle the last date of firing of the ceramics and hence the archeological age can be determined from the TL glow curve. However it was reported that the TL glow curve could be faked by irradiating a copy with x-rays. Read The Full Paper