From the Mary Burwell Lute Tutor, c.1670, f.7 (full stops editorial):

The good stringes are made at Rome or about Rome and none that are good are made in any other place except the great strings and octaves that are made in Lyons att Fraunce and noe where else. They attribute that to the clymate and to the waters. The stringes are made of sheepes and catts gutte and are twisted with a good deale of art. To be good they must be hard and transparant smooth and well twisted hard and strong and now they are preserved in a white paper dipped in oyle of almonds or in a hogges bladder. They endure noe moisture nor any opressive heate noe more than the lute but they will have a temperate ayre and place but of the twoe the moisture is the worst. When they are open there goodnes is knowne thus holding the twoe ends in both hands and strikeing the string with the middle finger if they parte in twoe onely or if being laid uppon the lute they doe not jarre. If the twoe stringes can be made of one bunch they will agree the better but it is hard to find twoe good stringes of a length therefore you must choose them as neare as you can to the same bignes, the string must not be full of knotts or gowty or rugged nor be bigger in one place then in another.