Pliny: Natural History, Vol. IX (Loeb)

even put them on, and made the gold cheaper than the fragments of little stones. On the contrary, many admit no gems and seal with the gold itself. That was discovered in the principate of Claudius Caesar. And it is not the case that slaves now encircle iron with gold—others decorate themselves with mere gold—the origin of which license is declared by the very name of the institution in Samothrace.
24 At first it had been the custom to wear them on single fingers, those closest to the smallest. Thus we see in the statues of Numa and Servius Tullius. Afterward, they placed them on the finger next to the thumb, even in the likenesses of the gods, then it pleased them to give one also to the little finger. Gaul and Britain are said to have used the middle one. This one is now the only one excepted, all the others are burdened, and even the joints are privately [laden] with other smaller ones. There are those who gather them all on one little finger, others indeed only one on this one, with which they seal the sealer. That one, stored away as a rare thing and unworthy of the injury of use, is brought forth as from a sanctuary, so that even to have had one on the little finger might be a display of costlier equipment kept in storage. Now others show off their weight. For others, it is a labor to wear more than one, others

stuff the gold tinsel with a lighter material, thinking it a safer precaution for their anxiety about gems in case of a fall; others enclose poisons beneath the gems, just as Demosthenes, the greatest orator of Greece, and they have rings for the sake of death. Finally, even the most numerous crimes of wealth are committed by means of rings. What was that life of the ancients, what kind of innocence, in which nothing was sealed! Now even food and drink are defended from plunder by a ring. This is the progress achieved by legions of slaves, a foreign crowd in the house, and now a nomenclator an attendant who announces guests or slaves' names must be employed even for the sake of slaves. It was otherwise among the ancients, where individual Marcipores or Lucipores referring to slaves named after their masters, e.g., 'Marcius's boy' or 'Lucius's boy' of the masters' clans held all their sustenance in common, nor was there any need at home for any guard against the domestics.
27 Now feasts are prepared to be plundered and at the same time those who might plunder them, and it is not enough to have sealed even the keys themselves. Rings are pulled off from those heavy with sleep or dying, and the greater part of life’s business began to center around this instrument, from an uncertain time. We seem, however, to be able to understand the authority of that thing in foreign lands in the case of Polycrates, the tyrant of Samos, to whom that prized ring, cast into the sea, was returned when a fish was caught, about the 230th year of our city.