Artisan (except the stable master) require materials and resources to craft items. By processing raw materials the and crafting items the artisan gain experience and level. New crafting recipes are gradually released depending on the artisan level.
Each artisan has an artisan's tool to improve their work. You can improve the four characteristics of precision, masterpiece, speed and reputation. Precision increases the quality of the goods and their value, a masterpiece is particularly well made and has a 20% increase in sales, speed shortens the production time for manufacturing goods and reputation shortens the time when selling a product. The tool of every craftsman can be improved by shards and gold. The maximum value can be increased with jewels.