They had mastered weaving, but they did not stop there; they invented new methods of dyeing, using vegetable dyes instead of the customary animal colours of the Orient. Pliny says:
The Gaul imitates with herbs all colours, including Tyrian purple; they do not seek the mollusk on the sea bottom; they run no risk of being devoured by sea monsters; they do not exploit the anchorless deep to multiply the attractions of the courtesan, or to increase the powers of the seducer of another's wife. They gather the herbs like cereals, standing on the dry ground; although the colour that they derive does not bear washing. Luxury could thus be gratified with greater show at the cost of fewer dangers.
It is clear, then, according to Pliny, at one time, it was believed that the competition of Gallic dyers might have ruined the Oriental, and would have done so, had the tenacity of their vegetable colouring equalled its beauty. In another passage Pliny tells us that these Gallic stuffs were used especially by the slaves and the populace.
The wool industry made no less progress in Gaul than weaving and dyeing. From numerous passages in Juvenal and Martial it appears that the woollen clothing worn by the populace of Rome in the second century was woven in Gaul, particularly in the districts to-day known as Arras, Langres, Saintonge. Pliny attributes to the Gauls the invention of a wool, that, soaked in acid, became incombustible, and was used to make mattresses.
Glass-making was another art carried from the East across the Mediterranean into Gaul. Still another industry, metallurgy, after weaving, contributed greatly to enrich Gaul. Undoubtedly even before the Roman conquest, Gaul worked gold mines; it seems, however, that silver mines remained untouched until about the time of Augustus. At any rate, the discovery of some deposits of gold and silver then gave a spur to several flourishing industries; jewelry-making, and--an original Gallic industry of much importance--silver-plating and tinning. Here is another extract from Pliny, from which you will see that in those times they already made in France "Christofle" silver-plate:
They cover [writes Pliny] the copper with tin in such a way that it is difficult to distinguish it from silver. It is a Gallic invention. Later they began to do the same thing with silver, silver-plating especially the ornaments of horses and carriages. The merit of the invention belongs to the Biturigi, and the industry was developed in the city of Alesia. After the same fashion there has been spread everywhere a foolish profusion of objects not only silver-, but gold-plated. All that is called _cultus_, elegance!