Fairing is the procedure of identifying fragments of a single meteorite fal
l (that were separated during atmospheric passage or during terrestrial his
tory) by establishing the similarity of two or more meteorite fragments. We
argue that pairing is governed by two principles, that only a single misma
tch of properties is required to refute a proposed pairing, and that virtua
lly all pairings bear some degree of uncertainty. Using data distributions
for modern falls, we take a probability approach to estimate degrees of cer
tainty associated with proposed pairings, emphasizing the importance of unu
sual features. For new pairing criteria or new analytical additions to old
criteria, the degree of variation within individual meteorites must be deli
neated and the degree of variation within meteorite classes must be quantif
ied. Criteria for pairing can be divided into (1) parent body history indic
ators, (2) meteoroid space history indicators, and (3) terrestrial history
indicators. Included in these categories are 11 specific criteria, includin
g petrographic textures, mineralogy and mineral composition, terrestrial ag
e estimates, cosmic-ray exposure ages, and natural thermoluminescence (TL)
levels. Not all criteria are applicable to all meteorite types. About 2275
pairings suggested in the literature have been subjected to this analysis.
Many literature pairings, especially those involving common meteorite types
, bear large uncertainties due to lack of data.